我正在使用 Photos 框架（又名PhotoKit）。在我的应用程序中，我需要收集 Moments（类型为PHAssetCollection）。PHAssetCollection有一个属性CLLocation *approximateLocation。
但是NSPredicate，当我从 PhotoKit 检索 Moments 时，我无法正常工作。
-(void)getMomentsNearCoordinate:(CLLocationCoordinate2D)coordinate completionBlock:(PKAssetManagerArrayBlock)completionBlock{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
PHFetchOptions *options = [[PHFetchOptions alloc] init];
options.predicate = [NSPredicate predicateWithFormat:@"approximateLocation.coordinate.latitude < 37.0"];
self.moments = [PHAssetCollection fetchMomentsWithOptions:options];
// Convert PHCollection into NSArray
NSMutableArray *momentsArray = [[NSMutableArray alloc]initWithCapacity:self.moments.count];
[self.moments enumerateObjectsUsingBlock:^(PHAssetCollection *moment, NSUInteger idx, BOOL *stop) {
[momentsArray addObject:moment];
}];
dispatch_async(dispatch_get_main_queue(), ^{
completionBlock([NSArray arrayWithArray:momentsArray]);
});
});
}
调试器将停止
self.moments = [PHAssetCollection fetchMomentsWithOptions:options];
出现错误：
*** 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“获取选项中不支持的谓词：近似位置.coordinate.latitude < 37”
这看起来很奇怪，因为我可以用orNSPredicate来过滤。startDateendDate
无论如何，接下来我想我会尝试NSPredicatewith 块：
-(void)getMomentsNearCoordinate:(CLLocationCoordinate2D)coordinate completionBlock:(PKAssetManagerArrayBlock)completionBlock{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
PHFetchOptions *options = [[PHFetchOptions alloc] init];
options.predicate = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
// Logic goes here
return YES;
}];
self.moments = [PHAssetCollection fetchMomentsWithOptions:options];
// Convert PHCollection into NSArray
NSMutableArray *momentsArray = [[NSMutableArray alloc]initWithCapacity:self.moments.count];
[self.moments enumerateObjectsUsingBlock:^(PHAssetCollection *moment, NSUInteger idx, BOOL *stop) {
[momentsArray addObject:moment];
}];
dispatch_async(dispatch_get_main_queue(), ^{
completionBlock([NSArray arrayWithArray:momentsArray]);
});
});
}
调试器再次停在
self.moments = [PHAssetCollection fetchMomentsWithOptions:options];
带有不同的错误消息：
*** 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“获取选项中不支持的谓词：BLOCKPREDICATE(0x27d338)”
最后，我记得在CloudKit 文档中看到他们添加了对按距离过滤的新支持。然而，这是为了CKQuery，不是NSPredicate。无论如何，我决定试一试。我使用我的坐标进行CLLocationthen 调用：
-(void)getMomentsNearLocation:(CLLocation*)location completionBlock:(PKAssetManagerArrayBlock)completionBlock{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
PHFetchOptions *options = [[PHFetchOptions alloc] init];
options.predicate = [NSPredicate predicateWithFormat:@"distanceToLocation:fromLocation:(%K,%@) < %f",
location,
2.0];
self.moments = [PHAssetCollection fetchMomentsWithOptions:options];
// Convert PHCollection into NSArray
NSMutableArray *momentsArray = [[NSMutableArray alloc]initWithCapacity:self.moments.count];
[self.moments enumerateObjectsUsingBlock:^(PHAssetCollection *moment, NSUInteger idx, BOOL *stop) {
[momentsArray addObject:moment];
}];
dispatch_async(dispatch_get_main_queue(), ^{
completionBlock([NSArray arrayWithArray:momentsArray]);
});
});
}
你猜对了。错误：
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CLLocation rangeOfString:]: unrecognized selector sent to instance 0x19e3e350'
同时，我将遍历列表PHAssetCollections并手动计算它是否在CLLocation. 这将大大降低效率。