如何在 Realm 谓词中正确使用协议定义的属性？

Question

我正在尝试使用 Realm 实现缓存系统。

根据类，缓存应该有不同的长度。因此，我定义了一个 StalenessChecking 协议：

@protocol StalenessChecking <NSObject>

@required
//  nonatomic needed when using a getter
@property (readonly, nonatomic, getter=isStale) bool stale;

@optional
- (void) setStaleness: (NSTimeInterval) duration;

@end

和一个对象：

接口文件(DziObject.h)

#import "Realm.h"
#import "StalenessChecking.h"

@interface DziObject : RLMObject <StalenessChecking>
@property (readonly) NSDate* refresh;

@end

实现文件(DiObject.m)

#import 'DziObject.h'
@implementation DziObject
{
   NSTimeInterval stalenessInterval;
}
@synthesize stale = _stale;

- (instancetype)init
{
    self = [super init];
    if (self) {
    _refresh = [NSDate date];
    stalenessInterval = 120.0;
    }
return self;
}

- (bool) isStale {
     return [[NSDate dateWithTimeInterval:stalenessInterval sinceDate:_refresh] timeIntervalSinceReferenceDate]< [[NSDate date] timeIntervalSinceReferenceDate];
}

- (void)setStaleness:(NSTimeInterval) duration
{
    stalenessInterval = duration;
}
@end

然后我从 Facade 调用它们：

接口：

#import <Foundation/Foundation.h>

@interface SDK_Facade : NSObject

+ (void) createDziO;
@end

实施：

#import "SDK_Facade.h"
#import "DziObject.h"

@implementation SDK_Facade

+ (void) createDziO
{

DziObject *dziO = [[DziObject alloc] init];
// both work fine
if (dziO.isStale) {
    NSLog(@"Is stale");
}
if (dziO.stale) {
    NSLog(@"Is really stale");
}

// Query Realm for all results less than 2 minutes old
// TODO: -- currently crashes
RLMResults< DziObject *> * dzios = [DziObject objectsWhere:@"stale == %@", @YES];
NSLog(@"DziOs: %lu", (unsigned long)dzios.count);

// Persist your data easily
RLMRealm *realm = [RLMRealm defaultRealm];
[realm transactionWithBlock:^{
    [realm addObject:dziO];
}];

// Queries should update in realtime
    NSLog(@"DO: %lu", (unsigned long)dzios.count);

}

@end

我遇到了一个丑陋的崩溃：

Terminating app due to uncaught exception 'Invalid property name', reason: 'Property 'stale' not found in object of type 'DziObject'

Answer 1

您不能在模型 class 遵循的协议中定义 Realm 模型属性。它必须在 class 定义本身中完成。

@interface DziObject : RLMObject <StalenessChecking>
@property NSDate* refresh;
@property (getter=isStale) bool stale;
@end

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