不使用UIImagePickerController实现读取相册图片的方法

来源：互联网发布：小鱼儿主页最近域名编辑：程序博客网时间：2024/05/16 14:22

转载自：http://blog.ilovedev.com/blog/2013/11/03/bu-shi-yong-uiimagepickercontrollershi-xian-du-qu-xiang-ce-tu-pian-de-fang-fa/

在读取系统相册的图片时，一般的实现是使用UIImagePickerController控件，然后实现UIImagePickerControllerDelegate里面的两个回调方法。本文介绍一种不使用此控件，用ALAssetsLibrary类库枚举出相册下面的图片信息。

旧的常规实现代码如下：

- (void)button2Pressed:(id)sender{    UIImagePickerController* vc = [[UIImagePickerController alloc] init];    vc.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;    vc.delegate = self;    [self presentViewController:vc animated:YES completion:nil];    [vc release];}#pragma mark - UIImagePickerControllerDelegate- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{    // 图片在这里    UIImage* image = [info objectForKey:UIImagePickerControllerOriginalImage];    [self dismissViewControllerAnimated:YES completion:nil];}- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{    [self dismissViewControllerAnimated:YES completion:nil];}

使用新的方法，首先做以下两点： 1.引入头文件：#import (尖括号)AssetsLibrary/AssetsLibrary.h(尖括号) 2.在工程中引入库：AssetsLibrary.framework 具体代码如下：

// 打印信息，仅做演示- (void)printALAssetInfo:(ALAsset*)asset{    //取图片的url    NSString *photoURL=[NSString stringWithFormat:@"%@",asset.defaultRepresentation.url];    NSLog(@"photoURL:%@", photoURL);    // 取图片    UIImage* photo = [UIImage imageWithCGImage:asset.defaultRepresentation.fullScreenImage];    NSLog(@"PHOTO:%@", photo);    NSLog(@"photoSize:%@", NSStringFromCGSize(photo.size));    // 取图片缩图图    UIImage* photoThumbnail = [UIImage imageWithCGImage:asset.thumbnail];    NSLog(@"PHOTO2:%@", photoThumbnail);    NSLog(@"photoSize2:%@", NSStringFromCGSize(photoThumbnail.size));}-(void)loadImageFromPhotoLibrary{    // 为了防止界面卡住，可以异步执行    dispatch_async(dispatch_get_main_queue(), ^{        // 获取相册每个组里的具体照片        ALAssetsGroupEnumerationResultsBlock groupEnumerAtion = ^(ALAsset *result, NSUInteger index, BOOL *stop){            if (result!=nil) {                // 检查是否是照片，还可能是视频或其它的                // 所以这里我们还能类举出枚举视频的方法。。。                if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {                    [self printALAssetInfo:result];                }            }        };        //获取相册的组        ALAssetsLibraryGroupsEnumerationResultsBlock groupsEnumeration = ^(ALAssetsGroup* group, BOOL* stop){            if (group!=nil) {                NSString *groupInfo=[NSString stringWithFormat:@"%@",group];                NSLog(@"GROUP INFO:%@",groupInfo);                [group enumerateAssetsUsingBlock:groupEnumerAtion];            }        };        ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *error){            // 相册访问失败的回调，可以打印一下失败原因            NSLog(@"相册访问失败，ERROR:%@", [error localizedDescription]);        };        ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];        [library enumerateGroupsWithTypes:ALAssetsGroupAll                               usingBlock:groupsEnumeration                             failureBlock:failureblock];        [library release];         }); }// 同上面的原理，我们再做一个根据URL取图片及缩略图的方法- (void)loadImageForURL:(NSURL*)photoUrl{    ALAssetsLibrary *assetLibrary=[[ALAssetsLibrary alloc] init];    [assetLibrary assetForURL:photoUrl                  resultBlock:^(ALAsset *asset)     {         [self printALAssetInfo:asset];    }                 failureBlock:^(NSError *error)     {        NSLog(@"error=%@",error);    }];}

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