iOS開發之保存照片到本身建立的相簿

iOS開發之保存照片到系統相冊（Photo Album） ，

保存照片還能夠用ALAssetsLibrary，ALAssetsLibrary提供了咱們對iOS設備中的相片、視頻的訪問，是鏈接應用程序和相冊之間訪問的一個橋樑。

接下來，咱們來詳細講解一下關於系統相冊權限獲取、保存照片、建立本身的相簿等等功能。

建立本身的相簿

這也是一種比較建立的做法，建立本身的相簿，而後把照片或者視頻保存到本身的相簿中。相關代碼以下：

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library addAssetsGroupAlbumWithName:@"test" resultBlock:^(ALAssetsGroup *group) { //建立相簿成功 } failureBlock:^(NSError *error) { //失敗 }];

保存照片

這個方法也是將照片保存到系統相簿裏面，不是保存到本身建立的相簿裏面。代碼以下：

ALAssetsLibrary *library = [[ALAssetsLibrary alloc]init];
[library writeImageToSavedPhotosAlbum:image.CGImage orientation:(ALAssetOrientation)image.imageOrientation completionBlock:^(NSURL *asSetUrl,NSError *error){ if (error) { //失敗 }else{ UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"存儲成功" message:nil delegate:nil cancelButtonTitle:@"肯定" otherButtonTitles:nil, nil]; [alert show]; } }];

獲取權限

在保存照片以前，若是用戶關閉相冊權限，這個時候是保存失敗的。若是你不作任何處理，用戶是不會知道本身保存失敗了。因此，咱們能夠在保存照片以前，作出相應的提示。如何獲取這個權限呢？通常有兩種方法：

1. 建立相簿失敗

2. 保存照片失敗

在上面兩個方法建立本身的相簿和保存照片的失敗結果裏，咱們能夠彈出獲取照片權限失敗的提示。咱們拿第一個建立相簿失敗來舉例：

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library addAssetsGroupAlbumWithName:@"test" resultBlock:^(ALAssetsGroup *group) { //建立相簿成功 } failureBlock:^(NSError *error) { UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"存儲失敗" message:@"請打開 設置-隱私-照片 來進行設置" delegate:nil cancelButtonTitle:@"肯定" otherButtonTitles:nil, nil]; [alert show]; }];

在保存照片失敗的結果裏，咱們也能夠彈出相應的提示，讓用戶打開應用程序的相冊權限。

保存照片到本身的相簿

下面這段代碼是在大谷歌裏面找到的，親自測試過是能夠用的，整理以下：

#pragma mark - 建立相冊 - (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; } } }; //建立相簿 [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAlbum usingBlock:listGroupBlock failureBlock:nil]; [self saveToAlbumWithMetadata:nil imageData:UIImagePNGRepresentation(self.image) customAlbumName:@"iOSDevTip" completionBlock:^ { //這裏能夠建立添加成功的方法 } failureBlock:^(NSError *error) { //處理添加失敗的方法顯示alert讓它回到主線程執行，否則那個框框死活不願彈出來 dispatch_async(dispatch_get_main_queue(), ^{ //添加失敗通常是由用戶不容許應用訪問相冊形成的，這邊能夠取出這種狀況加以判斷一下 if([error.localizedDescription rangeOfString:@"User denied access"].location != NSNotFound ||[error.localizedDescription rangeOfString:@"用戶拒絕訪問"].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(); } } }]; }

ALAssetsLibrary+CustomPhotoAlbum保存照片

github上有一個項目ALAssetsLibrary+CustomPhotoAlbum，講保存照片作了很好的封裝。使用以前記得先導入頭文件：

#import "ALAssetsLibrary+CustomPhotoAlbum.h"

保存照片到本身的相簿，直接調用：

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library saveImage:self.image toAlbum:@"gang" completion:^(NSURL *assetURL, NSError *error) { if (!error) { } } failure:^(NSError *error) { }];

ALAssetsLibrary+CustomPhotoAlbum對保存視頻的封裝也是很是好的。