来自 CloudKit 查询的 UITableView 部分
UITableView Sections from CloudKit Query
我有一个简单的 CloudKit 记录，它有两个字段，姓名和等级。我希望能够查询 CloudKit 返回所有记录，但按等级分组。我知道我可以用 NSFetchResultsController 做到这一点，但似乎找不到用 CKQuery 做到这一点的简单方法。
当前获取代码：
func fetchTeachers(_ completion: @escaping (_ teachers: [CKRecord]?, _ error: NSError?) -> () ) {
let query = CKQuery(recordType: TeacherType, predicate: NSPredicate(value: true))
query.sortDescriptors = [NSSortDescriptor(key:"Grade",ascending:true)]
publicDB.perform(query, inZoneWith: nil) { results, error in
completion(results, error as NSError?)
}
}
就像模型一样，您可以为 tableView 编写类似于此的内容。您可以编辑仪表板条目或键以根据需要进行排序。
Teachers.swift
class Teachers: NSObject {
var recordID: CKRecordID!
var name: String!
var grade: String!
}
您可能有这样的提交 class。
SubmitViewController.swift
//There can be a fail at any time so CloudKit send methods have an
//error being passed into the closure. You can set an isDirty property.
CKContainer.default().publicCloudDatabase.save(teacherRecord) { [unowned self] record, error in
DispatchQueue.main.async {
//code
ViewController.dirty = true
//code }
ViewController.swift
//Property that will store an array of Teachers
//objects so that you can show them in a table view
var teachers = [Teachers]()
//A “dirty” flag tracks when the derived data is out of sync with the primary data.
//It is set when the primary data changes. If the flag is set when the derived data
//is needed, then it is reprocessed and the flag is cleared. Otherwise,
//the previous cached derived data is used.
static var isDirty = true
//viewWillAppear() is going to clear the table view's selection if it has one,
//then it will use the isDirty flag to call loadTeachers() if it's needed.
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if let indexPath = tableView.indexPathForSelectedRow {
tableView.deselectRow(at: indexPath, animated: true)
}
if ViewController.dirty {
loadTeachers()
}
}
func loadTeachers() {
let pred = NSPredicate(value: true)
let sort = NSSortDescriptor(key: "creationDate", ascending: true)
let query = CKQuery(recordType: "TeacherType", predicate: pred)
query.sortDescriptors = [sort]
let operation = CKQueryOperation(query: query)
//Set the desiredKeys property to be an array of the record keys you want
operation.desiredKeys = ["name", "grade"]
operation.resultsLimit = 25
//CKQueryOperation has two closures. One streams records and one is
//called when the records have been downloaded. To handle this you
//can create a new array that will hold the teachers as they are parsed.
var newTeachers = [Teachers]()
//Set a recordFetchedBlock closure on the CKQueryOperation object.
//This will be given a CKRecord value for every record that gets
//downloaded, and the convert that into a Teachers object.
operation.recordFetchedBlock = { record in
let teacher = Teachers()
teacher.recordID = record.recordID
teacher.name = record["name"] as! String
teacher.grade = record["grade"] as! String
newTeachers.append(teacher)
}
//Called by CloudKit when all records have been downloaded, and will be
//given two parameters: a query cursor and an error if there was one.
//The query cursor is useful if you want to implement paging.
operation.queryCompletionBlock = { [unowned self] (cursor, error) in
DispatchQueue.main.async {
if error == nil {
self.teachers = newTeachers
self.tableView.reloadData()
} else {
let ac = UIAlertController(title: "Fetch failed", message: "Please try again: \(error!.localizedDescription)", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "OK", style: .default))
self.present(ac, animated: true)
}
}
}
//Ask CloudKit to run it
CKContainer.default().publicCloudDatabase.add(operation)
} //End of loadTeachers()
确认：
- 您是否在 CloudKit 仪表板中看到了您的数据？
- 您在读写时是否命名了您的记录类型"TeacherType"？
- 对于元数据索引，您是否select在 ID 旁边查询，在日期旁边排序
已创建？
- 您的设备在线吗？
*在 Paul 的帮助下。
要将检索到的 CKRecords 数组拆分为多个部分以便在 UITableView 中显示，您可以使用下面的帮助程序 class。
（CKQuery 本身不提供执行此分段的功能 - 它仅使您能够检索记录数组，可选择排序。）
使用 SectionedCKRecords class:
首先，使用 CKQuery 从 CloudKit 中获取所需的记录。 （您的示例代码已经这样做了。）这将为您提供一组 CKRecords。
让我们假设这些记录（根据您的示例代码）包含一个存储字符串值的“Grade”键，并且您希望根据以下条件将记录拆分为多个部分“等级”。
简单：
1.) 使用 CKRecords 数组和所需的 sectionNameKey:
初始化 SectionedCKRecords
let sectionedRecords = SectionedCKRecords(records: records, sectionNameKey: "Grade")
2.) 实现您的 UITableViewDataSource 以调用 sectionedRecords:
上的适当方法
SectionedCKRecords exposes methods similar to those of NSFetchedResultsController.
class YourDataSource: UITableViewDataSource {
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let record = sectionedRecords.record(at: indexPath)
// TODO: construct a UITableViewCell based on the record
// ...
}
func numberOfSections(in tableView: UITableView) -> Int {
return sectionedRecords.sections.count
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return sectionedRecords.sections[section].numberOfRecords
}
func sectionIndexTitles(for tableView: UITableView) -> [String]? {
return sectionedRecords.sectionIndexTitles
}
// etc...
}
自定义 sectionIndexTitle 行为：
如果您想自定义 sectionIndexTitles 的生成方式，您可以将 sectionIndexTitleForSectionName 闭包传递给 SectionedCKRecords 初始化程序。
By default, SectionedCKRecords matches the behavior of NSFetchedResultsController for generating sectionIndexTitles, using the capitalized first letter of the section name.
闭包将字符串（sectionName）作为输入，returns sectionIndexTitle。
SectionIndexTitleForSectionName 结构中提供了一些示例闭包。
示例：
let sectionedRecords = SectionedCKRecords(records: records, sectionNameKey: "Grade", sectionIndexTitleForSectionName: SectionIndexTitleForSectionName.firstLetterOfString)
SectionedCKRecords.swift: (Swift 3)
// SectionedCKRecords.swift (Swift 3)
// © 2016 @breakingobstacles (http://whosebug.com/users/57856/breakingobstacles)
// Source:
//
// License: The MIT License (https://opensource.org/licenses/MIT)
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
import UIKit
import CloudKit
// MARK: - SectionedCKRecords
class SectionedCKRecords {
private let sectionNameToSection: [String: Int]
private let sectionIndex: [String]
private let sectionIndexTitleToFirstSection: [String: Int]
init(records: [CKRecord], sectionNameKey: String, sectionIndexTitleForSectionName: (String) -> String? = SectionIndexTitleForSectionName.firstLetterOfString) {
self.records = records
self.sectionNameKey = sectionNameKey
// split records into sections
let splitResults = split(records: records, bySectionNameKey: sectionNameKey)
self.sections = splitResults.sections
self.sectionNameToSection = splitResults.sectionNameToSection
// build section index
var sectionIndex: [String] = []
var sectionIndexTitleToFirstSection: [String: Int] = [:]
for (index, section) in splitResults.sections.enumerated() {
guard let sectionIndexTitle = sectionIndexTitleForSectionName(section.name) else {
continue
}
section.indexTitle = sectionIndexTitle
if sectionIndexTitleToFirstSection.index(forKey: sectionIndexTitle) == nil {
sectionIndex.append(sectionIndexTitle)
sectionIndexTitleToFirstSection[sectionIndexTitle] = index
}
}
self.sectionIndex = sectionIndex
self.sectionIndexTitleToFirstSection = sectionIndexTitleToFirstSection
}
/// MARK: - Configuring Information
// The input array of records.
let records: [CKRecord]
// The key on the CKRecords used to determine the section they belong to. Assumes that record[sectionNameKey] returns a String value.
let sectionNameKey: String
/// MARK: - Accessing Results
// Returns the record at the given index path in the sectioned records.
func record(at indexPath: IndexPath) -> CKRecord {
return sections[indexPath.section].records[indexPath.row]
}
/// MARK: - Querying Section Information
// The sections for the fetch results.
private(set) var sections: [SectionInfo]
// Returns the section number for a given section title and index in the section index.
func section(forSectionIndexTitle sectionIndexTitle: String, at: Int) -> Int {
return sectionIndexTitleToFirstSection[sectionIndexTitle] ?? -1
}
// The array of section index titles.
var sectionIndexTitles: [String] {
get {
return sectionIndex
}
}
}
class SectionInfo: CustomStringConvertible {
var numberOfRecords: Int { return records.count }
let name: String
fileprivate(set) var indexTitle: String?
private(set) var records: [CKRecord]
init(name: String, indexTitle: String? = nil, records: [CKRecord] = []) {
self.name = name
self.indexTitle = indexTitle
self.records = records
}
fileprivate func add(record: CKRecord) {
records.append(record)
}
// MARK: - CustomStringConvertible
var description: String {
return "SectionInfo(name: \"\(name)\", indexTitle: \(indexTitle), numberOfRecords: \(numberOfRecords), records: \(records))"
}
}
// Example options for mapping section names to section index titles:
struct SectionIndexTitleForSectionName {
static let firstLetterOfString = { (string: String) -> String? in
guard let firstCharacter = (string as String).characters.first else {
return ""
}
return String(firstCharacter).uppercased()
}
static let fullString = { (string: String) -> String? in
return string as String
}
static let fullStringUppercased = { (string: String) -> String? in
return (string as String).uppercased()
}
}
/// split(records:bySectionNameKey)
///
/// Takes an input array of CKRecords, and splits them into sections using the (String) value retrieved from each record's "sectionNameKey".
///
/// The relative ordering of the records in the input array is maintained in each section.
///
/// - parameter records: An array of records to be split into sections.
/// - parameter bySectionNameKey: The key on the CKRecords used to determine the section they belong to.
/// Assumes that record[sectionNameKey] returns a String value.
///
/// - returns: An array of sections, and a dictionary mapping sectionName -> the index in the sections array.
func split(records: [CKRecord], bySectionNameKey sectionNameKey: String) -> (sections: [SectionInfo], sectionNameToSection: [String: Int])
{
func sectionName(forRecord record: CKRecord, withSectionNameKey sectionNameKey: String) -> String? {
guard let sectionNameValue = record.object(forKey: sectionNameKey) else {
assertionFailure("Record is missing expected sectionNameKey (\(sectionNameKey)): \(record)")
return nil
}
guard let sectionName = sectionNameValue as? String else {
assertionFailure("Record[\(sectionNameKey)] contains a value that cannot be converted directly to String. Record: \(record)")
return nil
}
return sectionName
}
var sections: [SectionInfo] = []
var sectionNameToSection: [String: Int] = [:]
var currentSection: SectionInfo? = nil
for record in records {
guard let sectionName = sectionName(forRecord: record, withSectionNameKey: sectionNameKey) else {
assertionFailure("Unable to obtain expected sectionNameKey (\(sectionNameKey)) for record: \(record)")
continue
}
if let currentSection = currentSection, currentSection.name == sectionName {
currentSection.add(record: record)
}
else {
// find existing section, if present
if let desiredSectionIndex = sectionNameToSection[sectionName] {
sections[desiredSectionIndex].add(record: record)
}
else {
// create new section
let newSection = SectionInfo(name: sectionName, records: [record])
sections.append(newSection)
sectionNameToSection[sectionName] = sections.count - 1
currentSection = newSection
}
}
}
return (sections: sections, sectionNameToSection: sectionNameToSection)
}
我有一个简单的 CloudKit 记录，它有两个字段，姓名和等级。我希望能够查询 CloudKit 返回所有记录，但按等级分组。我知道我可以用 NSFetchResultsController 做到这一点，但似乎找不到用 CKQuery 做到这一点的简单方法。
当前获取代码：
func fetchTeachers(_ completion: @escaping (_ teachers: [CKRecord]?, _ error: NSError?) -> () ) {
let query = CKQuery(recordType: TeacherType, predicate: NSPredicate(value: true))
query.sortDescriptors = [NSSortDescriptor(key:"Grade",ascending:true)]
publicDB.perform(query, inZoneWith: nil) { results, error in
completion(results, error as NSError?)
}
}
就像模型一样，您可以为 tableView 编写类似于此的内容。您可以编辑仪表板条目或键以根据需要进行排序。
Teachers.swift
class Teachers: NSObject {
var recordID: CKRecordID!
var name: String!
var grade: String!
}
您可能有这样的提交 class。
SubmitViewController.swift
//There can be a fail at any time so CloudKit send methods have an
//error being passed into the closure. You can set an isDirty property.
CKContainer.default().publicCloudDatabase.save(teacherRecord) { [unowned self] record, error in
DispatchQueue.main.async {
//code
ViewController.dirty = true
//code }
ViewController.swift
//Property that will store an array of Teachers
//objects so that you can show them in a table view
var teachers = [Teachers]()
//A “dirty” flag tracks when the derived data is out of sync with the primary data.
//It is set when the primary data changes. If the flag is set when the derived data
//is needed, then it is reprocessed and the flag is cleared. Otherwise,
//the previous cached derived data is used.
static var isDirty = true
//viewWillAppear() is going to clear the table view's selection if it has one,
//then it will use the isDirty flag to call loadTeachers() if it's needed.
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if let indexPath = tableView.indexPathForSelectedRow {
tableView.deselectRow(at: indexPath, animated: true)
}
if ViewController.dirty {
loadTeachers()
}
}
func loadTeachers() {
let pred = NSPredicate(value: true)
let sort = NSSortDescriptor(key: "creationDate", ascending: true)
let query = CKQuery(recordType: "TeacherType", predicate: pred)
query.sortDescriptors = [sort]
let operation = CKQueryOperation(query: query)
//Set the desiredKeys property to be an array of the record keys you want
operation.desiredKeys = ["name", "grade"]
operation.resultsLimit = 25
//CKQueryOperation has two closures. One streams records and one is
//called when the records have been downloaded. To handle this you
//can create a new array that will hold the teachers as they are parsed.
var newTeachers = [Teachers]()
//Set a recordFetchedBlock closure on the CKQueryOperation object.
//This will be given a CKRecord value for every record that gets
//downloaded, and the convert that into a Teachers object.
operation.recordFetchedBlock = { record in
let teacher = Teachers()
teacher.recordID = record.recordID
teacher.name = record["name"] as! String
teacher.grade = record["grade"] as! String
newTeachers.append(teacher)
}
//Called by CloudKit when all records have been downloaded, and will be
//given two parameters: a query cursor and an error if there was one.
//The query cursor is useful if you want to implement paging.
operation.queryCompletionBlock = { [unowned self] (cursor, error) in
DispatchQueue.main.async {
if error == nil {
self.teachers = newTeachers
self.tableView.reloadData()
} else {
let ac = UIAlertController(title: "Fetch failed", message: "Please try again: \(error!.localizedDescription)", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "OK", style: .default))
self.present(ac, animated: true)
}
}
}
//Ask CloudKit to run it
CKContainer.default().publicCloudDatabase.add(operation)
} //End of loadTeachers()
确认：
- 您是否在 CloudKit 仪表板中看到了您的数据？
- 您在读写时是否命名了您的记录类型"TeacherType"？
- 对于元数据索引，您是否select在 ID 旁边查询，在日期旁边排序 已创建？
- 您的设备在线吗？
*在 Paul 的帮助下。
要将检索到的 CKRecords 数组拆分为多个部分以便在 UITableView 中显示，您可以使用下面的帮助程序 class。
（CKQuery 本身不提供执行此分段的功能 - 它仅使您能够检索记录数组，可选择排序。）
使用 SectionedCKRecords class:
首先，使用 CKQuery 从 CloudKit 中获取所需的记录。 （您的示例代码已经这样做了。）这将为您提供一组 CKRecords。
让我们假设这些记录（根据您的示例代码）包含一个存储字符串值的“Grade”键，并且您希望根据以下条件将记录拆分为多个部分“等级”。
简单：
1.) 使用 CKRecords 数组和所需的 sectionNameKey:
初始化 SectionedCKRecordslet sectionedRecords = SectionedCKRecords(records: records, sectionNameKey: "Grade")
2.) 实现您的 UITableViewDataSource 以调用 sectionedRecords:
上的适当方法SectionedCKRecords exposes methods similar to those of NSFetchedResultsController.
class YourDataSource: UITableViewDataSource {
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let record = sectionedRecords.record(at: indexPath)
// TODO: construct a UITableViewCell based on the record
// ...
}
func numberOfSections(in tableView: UITableView) -> Int {
return sectionedRecords.sections.count
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return sectionedRecords.sections[section].numberOfRecords
}
func sectionIndexTitles(for tableView: UITableView) -> [String]? {
return sectionedRecords.sectionIndexTitles
}
// etc...
}
自定义 sectionIndexTitle 行为：
如果您想自定义 sectionIndexTitles 的生成方式，您可以将 sectionIndexTitleForSectionName 闭包传递给 SectionedCKRecords 初始化程序。
By default, SectionedCKRecords matches the behavior of NSFetchedResultsController for generating
sectionIndexTitles, using the capitalized first letter of the section name.
闭包将字符串（sectionName）作为输入，returns sectionIndexTitle。
SectionIndexTitleForSectionName 结构中提供了一些示例闭包。
示例：
let sectionedRecords = SectionedCKRecords(records: records, sectionNameKey: "Grade", sectionIndexTitleForSectionName: SectionIndexTitleForSectionName.firstLetterOfString)
SectionedCKRecords.swift: (Swift 3)
// SectionedCKRecords.swift (Swift 3)
// © 2016 @breakingobstacles (http://whosebug.com/users/57856/breakingobstacles)
// Source:
//
// License: The MIT License (https://opensource.org/licenses/MIT)
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
import UIKit
import CloudKit
// MARK: - SectionedCKRecords
class SectionedCKRecords {
private let sectionNameToSection: [String: Int]
private let sectionIndex: [String]
private let sectionIndexTitleToFirstSection: [String: Int]
init(records: [CKRecord], sectionNameKey: String, sectionIndexTitleForSectionName: (String) -> String? = SectionIndexTitleForSectionName.firstLetterOfString) {
self.records = records
self.sectionNameKey = sectionNameKey
// split records into sections
let splitResults = split(records: records, bySectionNameKey: sectionNameKey)
self.sections = splitResults.sections
self.sectionNameToSection = splitResults.sectionNameToSection
// build section index
var sectionIndex: [String] = []
var sectionIndexTitleToFirstSection: [String: Int] = [:]
for (index, section) in splitResults.sections.enumerated() {
guard let sectionIndexTitle = sectionIndexTitleForSectionName(section.name) else {
continue
}
section.indexTitle = sectionIndexTitle
if sectionIndexTitleToFirstSection.index(forKey: sectionIndexTitle) == nil {
sectionIndex.append(sectionIndexTitle)
sectionIndexTitleToFirstSection[sectionIndexTitle] = index
}
}
self.sectionIndex = sectionIndex
self.sectionIndexTitleToFirstSection = sectionIndexTitleToFirstSection
}
/// MARK: - Configuring Information
// The input array of records.
let records: [CKRecord]
// The key on the CKRecords used to determine the section they belong to. Assumes that record[sectionNameKey] returns a String value.
let sectionNameKey: String
/// MARK: - Accessing Results
// Returns the record at the given index path in the sectioned records.
func record(at indexPath: IndexPath) -> CKRecord {
return sections[indexPath.section].records[indexPath.row]
}
/// MARK: - Querying Section Information
// The sections for the fetch results.
private(set) var sections: [SectionInfo]
// Returns the section number for a given section title and index in the section index.
func section(forSectionIndexTitle sectionIndexTitle: String, at: Int) -> Int {
return sectionIndexTitleToFirstSection[sectionIndexTitle] ?? -1
}
// The array of section index titles.
var sectionIndexTitles: [String] {
get {
return sectionIndex
}
}
}
class SectionInfo: CustomStringConvertible {
var numberOfRecords: Int { return records.count }
let name: String
fileprivate(set) var indexTitle: String?
private(set) var records: [CKRecord]
init(name: String, indexTitle: String? = nil, records: [CKRecord] = []) {
self.name = name
self.indexTitle = indexTitle
self.records = records
}
fileprivate func add(record: CKRecord) {
records.append(record)
}
// MARK: - CustomStringConvertible
var description: String {
return "SectionInfo(name: \"\(name)\", indexTitle: \(indexTitle), numberOfRecords: \(numberOfRecords), records: \(records))"
}
}
// Example options for mapping section names to section index titles:
struct SectionIndexTitleForSectionName {
static let firstLetterOfString = { (string: String) -> String? in
guard let firstCharacter = (string as String).characters.first else {
return ""
}
return String(firstCharacter).uppercased()
}
static let fullString = { (string: String) -> String? in
return string as String
}
static let fullStringUppercased = { (string: String) -> String? in
return (string as String).uppercased()
}
}
/// split(records:bySectionNameKey)
///
/// Takes an input array of CKRecords, and splits them into sections using the (String) value retrieved from each record's "sectionNameKey".
///
/// The relative ordering of the records in the input array is maintained in each section.
///
/// - parameter records: An array of records to be split into sections.
/// - parameter bySectionNameKey: The key on the CKRecords used to determine the section they belong to.
/// Assumes that record[sectionNameKey] returns a String value.
///
/// - returns: An array of sections, and a dictionary mapping sectionName -> the index in the sections array.
func split(records: [CKRecord], bySectionNameKey sectionNameKey: String) -> (sections: [SectionInfo], sectionNameToSection: [String: Int])
{
func sectionName(forRecord record: CKRecord, withSectionNameKey sectionNameKey: String) -> String? {
guard let sectionNameValue = record.object(forKey: sectionNameKey) else {
assertionFailure("Record is missing expected sectionNameKey (\(sectionNameKey)): \(record)")
return nil
}
guard let sectionName = sectionNameValue as? String else {
assertionFailure("Record[\(sectionNameKey)] contains a value that cannot be converted directly to String. Record: \(record)")
return nil
}
return sectionName
}
var sections: [SectionInfo] = []
var sectionNameToSection: [String: Int] = [:]
var currentSection: SectionInfo? = nil
for record in records {
guard let sectionName = sectionName(forRecord: record, withSectionNameKey: sectionNameKey) else {
assertionFailure("Unable to obtain expected sectionNameKey (\(sectionNameKey)) for record: \(record)")
continue
}
if let currentSection = currentSection, currentSection.name == sectionName {
currentSection.add(record: record)
}
else {
// find existing section, if present
if let desiredSectionIndex = sectionNameToSection[sectionName] {
sections[desiredSectionIndex].add(record: record)
}
else {
// create new section
let newSection = SectionInfo(name: sectionName, records: [record])
sections.append(newSection)
sectionNameToSection[sectionName] = sections.count - 1
currentSection = newSection
}
}
}
return (sections: sections, sectionNameToSection: sectionNameToSection)
}