如何将PHAsset转换为Objective-C中的UIImage
我有一个数组填充PHAsset对象（ https://developer.apple.com/library/prerelease/ios/documentation/Photos/Reference/PHAsset_Class/index.html ），我想知道如何将它们转换成UIImage，然后将它们保存在一个数组中。
具有PHAsset对象的数组称为self.assets ，这是我到目前为止：
PHImageManager *manager = [PHImageManager defaultManager]; CGFloat scale = UIScreen.mainScreen.scale; NSMutableArray *images = [NSMutableArray arrayWithCapacity:[self.assets count]]; for (int i = 0; i < [self.assets count]; i++) { CGSize targetSize = CGSizeMake(scale, scale); [manager requestImageForAsset:[self.assets objectAtIndex:i] targetSize:targetSize contentMode:PHImageContentModeAspectFill options:self.requestOptions resultHandler:^(UIImage *image, NSDictionary *info){ [images addObject:image]; }]; }
self.requestOptions是.h中的一个属性
@property (nonatomic, strong) PHImageRequestOptions *requestOptions;
并在viewDidLoad我这样做：
self.requestOptions = [[PHImageRequestOptions alloc] init]; self.requestOptions.resizeMode = PHImageRequestOptionsResizeModeExact; self.requestOptions.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;
但是在做一些debugging之后，我一直看到self.assets有以下值：
( <PHAsset: 0x1743828a0> 3B6D658D-EC76-43A1-9793-35D889E9CF15/L0/001 mediaType=1/0, assetSource=3, (2448x2448), creationDate=2015-07-27 02:02:46 +0000, location=1, hidden=0, favorite=0 , <PHAsset: 0x174382970> 50F05575-71D2-446B-BD1E-8E3250E375AD/L0/001 mediaType=1/0, assetSource=3, (2448x2448), creationDate=2015-07-27 02:02:47 +0000, location=1, hidden=0, favorite=0 )
images是空的。 有谁知道我可以添加将PHAssets转换成UIImages，并将它们添加到images数组？ 任何帮助表示赞赏。 谢谢！
对于在这个问题上和我一样挣扎的人，这是要走的路。
首先将requestOptions设置为：
self.requestOptions = [[PHImageRequestOptions alloc] init]; self.requestOptions.resizeMode = PHImageRequestOptionsResizeModeExact; self.requestOptions.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat; // this one is key self.requestOptions.synchronous = YES;
如果数组中有多个资产用PHAsset对象填充，则添加以下代码：
self.assets = [NSMutableArray arrayWithArray:assets]; PHImageManager *manager = [PHImageManager defaultManager]; NSMutableArray *images = [NSMutableArray arrayWithCapacity:[assets count]]; // assets contains PHAsset objects. __block UIImage *ima; for (PHAsset *asset in self.assets) { // Do something with the asset [manager requestImageForAsset:asset targetSize:PHImageManagerMaximumSize contentMode:PHImageContentModeDefault options:self.requestOptions resultHandler:^void(UIImage *image, NSDictionary *info) { ima = image; [images addObject:ima]; }]; }
现在images数组包含所有的图像格式的图像。
Swift 3.0答案
let photoAsset = asset let manager = PHImageManager.default() var options: PHImageRequestOptions? options = PHImageRequestOptions() options?.resizeMode = .exact options?.isSynchronous = true manager.requestImage( for: photoAsset, targetSize: PHImageManagerMaximumSize, contentMode: .aspectFill, options: options ) { [weak self] result, _ in completion(result) }
选项？.isSynchronous = true非常重要
BOOL synchronous; // return only a single result, blocking until available (or failure). Defaults to NO