在刚刚在线上一篇文章 iOS开发之保存照片到系统相册(Photo Album) ,我们讲到了如何保持照片系统相册。还有其他保存的方法吗?
保存照片还可以用 ALAssetsLibrary
, ALAssetsLibrary
提供了我们对iOS设备中的相片、视频的访问,是连接应用程序和相册之间访问的一个桥梁。
接下来,我们来详细讲解一下关于系统相册权限获取、保存照片、创建自己的相簿等等功能。
这也是一种比较创建的作法,创建自己的相簿,然后把照片或者视频保存到自己的相簿中。相关代码如下:
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init]; [library addAssetsGroupAlbumWithName:@"test" resultBlock:^(ALAssetsGroup *group) { //创建相簿成功 } failureBlock:^(NSError *error) { //失败 }];
这个方法也是将照片保存到系统相簿里面,不是保存到自己创建的相簿里面。代码如下:
ALAssetsLibrary *library = [[ALAssetsLibrary alloc]init]; [library writeImageToSavedPhotosAlbum:image.CGImage orientation:(ALAssetOrientation)image.imageOrientation completionBlock:^(NSURL *asSetUrl,NSError *error){ if (error) { //失败 }else{ UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"存储成功" message:nil delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil]; [alert show]; } }];
在保存照片之前,如果用户关闭相册权限,这个时候是保存失败的。如果你不做任何处理,用户是不会知道自己保存失败了。所以,我们可以在保存照片之前,做出相应的提示。如何获取这个权限呢?一般有两种方法:
创建相簿失败
保存照片失败
在上面两个方法 创建自己的相簿 和 保存照片 的失败结果里,我们可以弹出获取照片权限失败的提示。我们拿第一个创建相簿失败来举例:
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init]; [library addAssetsGroupAlbumWithName:@"test" resultBlock:^(ALAssetsGroup *group) { //创建相簿成功 } failureBlock:^(NSError *error) { UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"存储失败" message:@"请打开 设置-隐私-照片 来进行设置" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil]; [alert show]; }];
在保存照片失败的结果里,我们也可以弹出相应的提示,让用户打开应用程序的相册权限。
下面这段代码是在大谷歌里面找到的,亲自测试过是可以用的,整理如下:
#pragma mark - 创建相册 - (void)createAlbum { ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init]; NSMutableArray *groups=[[NSMutableArray alloc]init]; ALAssetsLibraryGroupsEnumerationResultsBlock listGroupBlock = ^(ALAssetsGroup *group, BOOL *stop) { if (group) { [groups addObject:group]; } else { BOOL haveHDRGroup = NO; for (ALAssetsGroup *gp in groups) { NSString *name =[gp valueForProperty:ALAssetsGroupPropertyName]; if ([name isEqualToString:@"iOSDevTip"]) { haveHDRGroup = YES; } } if (!haveHDRGroup) { //do add a group named "XXXX" [assetsLibrary addAssetsGroupAlbumWithName:@"iOSDevTip" resultBlock:^(ALAssetsGroup *group) { [groups addObject:group]; } failureBlock:nil]; haveHDRGroup = YES; } } }; //创建相簿 [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAlbum usingBlock:listGroupBlock failureBlock:nil]; [self saveToAlbumWithMetadata:nil imageData:UIImagePNGRepresentation(self.image) customAlbumName:@"iOSDevTip" completionBlock:^ { //这里可以创建添加成功的方法 } failureBlock:^(NSError *error) { //处理添加失败的方法显示alert让它回到主线程执行,不然那个框框死活不肯弹出来 dispatch_async(dispatch_get_main_queue(), ^{ //添加失败一般是由用户不允许应用访问相册造成的,这边可以取出这种情况加以判断一下 if([error.localizedDescription rangeOfString:@"User denied access"].location != NSNotFound ||[error.localizedDescription rangeOfString:@"用户拒绝访问"].location!=NSNotFound){ UIAlertView *alert=[[UIAlertView alloc]initWithTitle:error.localizedDescription message:error.localizedFailureReason delegate:nil cancelButtonTitle:NSLocalizedString(@"ok", nil) otherButtonTitles: nil]; [alert show]; } }); }]; } - (void)saveToAlbumWithMetadata:(NSDictionary *)metadata imageData:(NSData *)imageData customAlbumName:(NSString *)customAlbumName completionBlock:(void (^)(void))completionBlock failureBlock:(void (^)(NSError *error))failureBlock { ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init]; __weak ALAssetsLibrary *weakSelf = assetsLibrary; void (^AddAsset)(ALAssetsLibrary *, NSURL *) = ^(ALAssetsLibrary *assetsLibrary, NSURL *assetURL) { [assetsLibrary assetForURL:assetURL resultBlock:^(ALAsset *asset) { [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) { if ([[group valueForProperty:ALAssetsGroupPropertyName] isEqualToString:customAlbumName]) { [group addAsset:asset]; if (completionBlock) { completionBlock(); } } } failureBlock:^(NSError *error) { if (failureBlock) { failureBlock(error); } }]; } failureBlock:^(NSError *error) { if (failureBlock) { failureBlock(error); } }]; }; [assetsLibrary writeImageDataToSavedPhotosAlbum:imageData metadata:metadata completionBlock:^(NSURL *assetURL, NSError *error) { if (customAlbumName) { [assetsLibrary addAssetsGroupAlbumWithName:customAlbumName resultBlock:^(ALAssetsGroup *group) { if (group) { [weakSelf assetForURL:assetURL resultBlock:^(ALAsset *asset) { [group addAsset:asset]; if (completionBlock) { completionBlock(); } } failureBlock:^(NSError *error) { if (failureBlock) { failureBlock(error); } }]; } else { AddAsset(weakSelf, assetURL); } } failureBlock:^(NSError *error) { AddAsset(weakSelf, assetURL); }]; } else { if (completionBlock) { completionBlock(); } } }]; }
github
上有一个项目 ALAssetsLibrary+CustomPhotoAlbum ,讲保存照片做了很好的封装。使用之前记得先导入头文件:
#import "ALAssetsLibrary+CustomPhotoAlbum.h"
保存照片到自己的相簿,直接调用:
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init]; [library saveImage:self.image toAlbum:@"gang" completion:^(NSURL *assetURL, NSError *error) { if (!error) { } } failure:^(NSError *error) { }];
ALAssetsLibrary+CustomPhotoAlbum
对保存视频的封装也是非常好的。我现在项目中用的也是这个第三方来保存照片和视频。因为不错,所以推荐给大家使用。