比较两个 NSArray 并检测变化的最佳方法是什么

Question

我的要求是确定地址簿中的更改（自上次打开应用程序以来更改了哪些联系人和哪些字段。

现在我有两个 NSArrays 作为 arrSavedContacts（包含以前的地址簿联系人）和 arrContacts（当前地址簿联系人）。这就是两个数组的样子

arrSavedContacts

{
    firstName = Gayan;
    id = 224;
    lastName = Udaha;
    phones =         (
                    {
            label = Mobile;
            value = "123456789";
        }
    );
},
    {
    firstName = Chandrananda;
    id = 225;
    lastName = "";
    phones =         (
                    {
            label = Mobile;
            value = "234567891";
        }
    );
},
    {
    firstName = Joe;
    id = 228;
    lastName = B8;
    phones =         (
                    {
            label = Mobile;
            value = "345678912";
        }
    );
},

arr联系人

{
    firstName = FirstName Changed;
    id = 224;
    lastName = Udaha;
    phones =         (
                    {
            label = Mobile;
            value = "123456789";
        }
    );
},
    {
    firstName = Chandrananda;
    id = 225;
    lastName = "";
    phones =         (
                    {
            label = Mobile;
            value = "345678912";
        }
    );
},

对于上面的两个数组，我们可以注意到两个变化，第 3 项被删除，第 1 项中的 firstName 被更改。

由于地址簿中可以有数千个项目，我的问题是，比较这两个数组并检测更改的项目（删除、添加、内部字段的更改）的最佳和最佳方法是什么？

非常感谢代码示例

Answer 1

继续 rmaddy 的建议，将数据放在字典的字典中，以便根据唯一 ID 轻松找出第一个位置的删除是有意义的。例如，这就是您的基本字典的样子：

{ 224 = {
        firstName = Gayan;
        id = 224;
        lastName = Udaha;
        phones = (
               {
                 label = Mobile;
                 value = "123456789";
               }
                );
        }

    225 = {
        firstName = Chandrananda;
        id = 225;
        lastName = "";
        phones =  (
               {
                 label = Mobile;
                 value = "234567891";
                }
                 );
    }
}

现在，一旦您的数据设置正确，您就可以在 NSDictionary 上添加一个类别并实现以下方法：

- (NSArray*)changedKeysIn:(NSDictionary*)iAnotherDict {
    NSMutableArray *changedKeys = [NSMutableArray array];

    for (id key in self) {
        if(![[self objectForKey:key] isEqual:[iAnotherDict objectForKey:key]])
            [changedKeys addObject:key];
        }

        return changedKeys;
}

然后简单地称它为：

[baseDict changedKeysIn:anotherDict];

Answer 2

这是检查更改、添加和删除的代码。请查收，如有不明白请评论...

NSMutableArray *oldArr =[NSMutableArray arrayWithArray:@[@{
                                                             @"firstName" : @"Gayan",
                                                             @"id" : @224,
                                                             @"lastName" : @"Udaha",
                                                             @"phones": @[
                                                                     @{
                                                                         @"label" : @"Mobile",
                                                                         @"value" : @"123456789"
                                                                      }
                                                                     ]
                                                             },
                                                         @{
                                                             @"firstName" : @"Chandrananda",
                                                             @"id" : @225,
                                                             @"lastName" : @"",
                                                             @"phones": @[
                                                                     @{
                                                                         @"label" : @"Mobile",
                                                                         @"value" : @"234567891"
                                                                         }
                                                                     ]
                                                             },
                                                         @{
                                                             @"firstName" : @"Joe",
                                                             @"id" : @226,
                                                             @"lastName" : @"",
                                                             @"phones": @[
                                                                     @{
                                                                         @"label" : @"Mobile",
                                                                         @"value" : @"345678912"
                                                                         }
                                                                     ]
                                                             },
]];

NSMutableArray *newArr =[NSMutableArray arrayWithArray:@[@{
                                                             @"firstName" : @"Gayan",
                                                             @"id" : @224,
                                                             @"lastName" : @"Udaha",
                                                             @"phones": @[
                                                                     @{
                                                                         @"label" : @"Mobile",
                                                                         @"value" : @"123456789"
                                                                         }
                                                                     ]
                                                             },
                                                         @{
                                                             @"firstName" : @"Chandrananda",
                                                             @"id" : @225,
                                                             @"lastName" : @"",
                                                             @"phones": @[
                                                                     @{
                                                                         @"label" : @"Mobile",
                                                                         @"value" : @"11111111"
                                                                         }
                                                                     ]
                                                             },
                                                         @{
                                                             @"firstName" : @"Luan",
                                                             @"id" : @229,
                                                             @"lastName" : @"",
                                                             @"phones": @[
                                                                     @{
                                                                         @"label" : @"Mobile",
                                                                         @"value" : @"55555555"
                                                                         }
                                                                     ]
                                                             },
                                                         ]];


NSMutableSet *oldSet = [NSMutableSet setWithArray:oldArr];
NSMutableSet *newSet = [NSMutableSet setWithArray:newArr];

//1: Get filter all changed, add, delete items

[oldSet minusSet:newSet];
[newSet minusSet:oldSet];

NSArray *remainOldArr = [NSArray arrayWithArray:[oldSet allObjects]];
NSArray *remainNewArr = [NSArray arrayWithArray:[newSet allObjects]];

if (remainNewArr.count == 0 && remainOldArr.count == 0) {
    // there is no changes.
    return ;
}

//2: detect which items changed,add,delete

NSMutableArray *arrayChangedItems = nil;
NSMutableArray *arrayDeleteItems = nil;
NSMutableArray *arrayAddItems =nil;

NSPredicate *pre1 = [NSPredicate predicateWithFormat:@"self.id IN %@",[remainOldArr valueForKeyPath:@"id"]];
NSPredicate *pre2 = [NSPredicate predicateWithFormat:@"NOT self.id IN %@",[remainOldArr valueForKeyPath:@"id"]];
NSPredicate *pre3 = [NSPredicate predicateWithFormat:@"NOT self.id IN %@",[remainNewArr valueForKeyPath:@"id"]];

arrayChangedItems = [NSMutableArray arrayWithArray:[remainNewArr filteredArrayUsingPredicate:pre1]];
arrayAddItems = [NSMutableArray arrayWithArray:[remainNewArr filteredArrayUsingPredicate:pre2]];
arrayDeleteItems = [NSMutableArray arrayWithArray:[remainOldArr filteredArrayUsingPredicate:pre3]];

Answer 3

怎么样……

// put new contacts in a dictionary
NSMutableDictionary *aDictionary = [NSMutableDictionary dictionary];
[arrContacts enumerateObjectsUsingBlock:^(id theNewContact, NSUInteger idx, BOOL *stop)
{
    [aDictionary setObject:theNewContact forKey:[theNewContact valueForKey:@"id"]];
}];

// check each old contact
[arrSavedContacts enumerateObjectsUsingBlock:^(id theOldContact, NSUInteger idx, BOOL *stop)
{
    NSDictionary *aNewContact = [aDictionary objectForKey:[theOldContact valueForKey:@"id"]];
    if (aNewContact == nil)
    {
        // delete old contact
    }
    else
    {
        if (![aNewContact isEqual:theOldContact])
        {
            // update old contact
        }
        // remove existing contact from the dictionary
        [aDictionary removeObjectForKey:[theOldContact valueForKey:@"id"]];
    }
}];

// new contacts
[aDictionary allValues];

每个数组枚举一次。

比较两个 NSArray 并检测变化的最佳方法是什么

What is the best way to compare two NSArrays and detect changes

objective-c

nsdictionary

nsarray

nspredicate

ios