iOS 獲取系統(tǒng)相冊(cè)圖片

  • iOS獲取系統(tǒng)相冊(cè)圖片方法有三種：UIImagePickerController，AssetsLibrary和Photos。
    iOS 系統(tǒng)相冊(cè)

1. UIImagePickerController

  • 這種方法比較簡(jiǎn)單，但靈活性差，我們直接看實(shí)例。

1.1 初始化控制器

UIImagePickerController *pickerCtr = [[UIImagePickerController alloc] init];
pickerCtr.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
pickerCtr.delegate = self;

1.2 打開相冊(cè)

[self presentViewController:pickerCtr animated:YES completion:nil];

1.3 選擇某個(gè)圖片時(shí)系統(tǒng)調(diào)用代理方法

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info {
    
    NSString *type = [info objectForKey:UIImagePickerControllerMediaType];
    if ([type isEqualToString:@"public.image"]) {
        UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
        //process image
        [picker dismissViewControllerAnimated:YES completion:nil];
    }
}

1.4 取消選擇圖片時(shí)系統(tǒng)調(diào)用代理方法

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    [picker dismissViewControllerAnimated:YES completion:nil];
}

2. AssetsLibrary（已經(jīng)在iOS8拋棄了）

  • 這種方法比較高級(jí)，自由性強(qiáng)，基本滿足你所有操作，當(dāng)然不能滿足你也無(wú)能為力了，沒有其他方法了。

2.1導(dǎo)入頭文件

#import <AssetsLibrary/AssetsLibrary.h>

2.2創(chuàng)建AssetsLibrary對(duì)象并初始化

//在@interface中
@property (nonatomic, strong) ALAssetsLibrary *photoLibrary;

//在@implementation
- (ALAssetsLibrary *)photoLibrary {
    if (!_photoLibrary) {
        _photoLibrary = [[ALAssetsLibrary alloc] init];
    }
    return _photoLibrary;
}

2.3 獲取相冊(cè)圖片信息

  • ALAssetsGroupType相冊(cè)類型
ALAssetsGroupLibrary     NS_ENUM_DEPRECATED_IOS(4_0, 9_0) = (1 << 0),         // The Library group that includes all assets.
ALAssetsGroupAlbum       NS_ENUM_DEPRECATED_IOS(4_0, 9_0) = (1 << 1),         // All the albums synced from iTunes or created on the device.
ALAssetsGroupEvent       NS_ENUM_DEPRECATED_IOS(4_0, 9_0) = (1 << 2),         // All the events synced from iTunes.
ALAssetsGroupFaces       NS_ENUM_DEPRECATED_IOS(4_0, 9_0) = (1 << 3),         // All the faces albums synced from iTunes.
ALAssetsGroupSavedPhotos NS_ENUM_DEPRECATED_IOS(4_0, 9_0) = (1 << 4),         // The Saved Photos album.
#if __IPHONE_5_0 <= __IPHONE_OS_VERSION_MAX_ALLOWED
ALAssetsGroupPhotoStream NS_ENUM_DEPRECATED_IOS(5_0, 9_0) = (1 << 5),         // The PhotoStream album.
#endif
ALAssetsGroupAll         NS_ENUM_DEPRECATED_IOS(4_0, 9_0) = 0xFFFFFFFF,       // The same as ORing together all the available group types,
  • ALAssetsFilter相冊(cè)過濾器
//Get all photos assets in the assets group.
allPhotos;
// Get all video assets in the assets group.
allVideos;
// Get all assets in the group.
allAssets;
  • group中獲取圖片方法
/**
@param NSIndexSet               需要獲取的相冊(cè)中圖片范圍
@param NSEnumerationOptions     獲取圖片的順序（順序還是逆序）
//ALAssetsGroupEnumerationResultsBlock的參數(shù)
@param result                   照片ALAsset對(duì)象
@param index                    當(dāng)前result在該group相冊(cè)中的位置，第index位置上
@param *stop                    需要停止的時(shí)候 *stop = YES就停止繼續(xù)運(yùn)行當(dāng)前相冊(cè)group
*/
enumerateAssetsAtIndexes:(NSIndexSet *)indexSet options:(NSEnumerationOptions)options usingBlock:(ALAssetsGroupEnumerationResultsBlock)enumerationBlock
  • ** 該開始獲取相冊(cè)圖片了**
- (void)getPhotoAlbumAsset {
    
    [self.photoLibrary enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
        
        //只讀圖片
        [group setAssetsFilter:[ALAssetsFilter allPhotos]];
        //該相冊(cè)照片數(shù)量
        NSInteger photoNumber = [group numberOfAssets];
        
        NSIndexSet *IndexSet = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, photoNumber)];
        [group enumerateAssetsAtIndexes:IndexSet options:NSEnumerationReverse usingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {
            
            if([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {
                
                ALAssetRepresentation *representation = [result defaultRepresentation];
                NSURL *photoUrl = [representation url];
                NSDate *imageDate = [result valueForProperty:ALAssetPropertyDate];

                //縮略圖
                UIImage *image1 = [UIImage imageWithCGImage:result.thumbnail];
                //屏幕分辨率圖
                UIImage *image2 = [representation fullScreenImage];
                //原圖
                UIImage *image3 = [representation fullScreenImage];
            }
        }];
        
        if (group == NULL) {
            NSLog(@"讀取所有相冊(cè)結(jié)束");
        }
        
    } failureBlock:^(NSError *error) {
        NSLog(@"獲取相冊(cè)圖片失敗");
    }];
}
  • 注意
  • group為NULL時(shí)，所有相冊(cè)都讀完了。
  • 如果多次循環(huán)訪問NSDictionary *metadata = [representation metadata]會(huì)內(nèi)存異常，原因是多次創(chuàng)建了metadata的字典，你的方法從當(dāng)前的runloop中返回前不會(huì)釋放內(nèi)存，因此內(nèi)存中加載了多個(gè)metadata。
    解決方法如下，沒有對(duì)象持有metadata時(shí)被自動(dòng)釋放:
@autoreleasepool  {
      metadata = [representation metadata]; 
}
  • 有些時(shí)候，先存儲(chǔ)圖片Url，需要的時(shí)候再讀圖片的需求，此時(shí)需要注意，這些Url只有在創(chuàng)建的photoLibrary的生命周期內(nèi)有效，如果photoLibrary銷毀了獲取的Url也失效。
  • 用Url獲取圖片方法
[self.photoLibrary assetForURL:photoUrl resultBlock:^(ALAsset *asset) {
     
      ALAssetRepresentation *representation = [result defaultRepresentation]; 
      NSURL *photoUrl = [representation url]; 
      //縮略圖 
      UIImage *image1 = [UIImage imageWithCGImage:result.thumbnail]; 
      //屏幕分辨率圖 
      UIImage *image2 = [representation fullScreenImage]; 
      //原圖 
      UIImage *image3 = [representation fullScreenImage];
  } failureBlock:^(NSError *error) {
}];

3. Photos

  • Photos是iOS8之后支持的相冊(cè)訪問的庫(kù)，蘋果重構(gòu)AssetsLibrary之后的產(chǎn)物。

3.1導(dǎo)入頭文件
#import <Photos/Photos.h>

3.2 設(shè)置需要檢索的相冊(cè)類型配置，需要照片或視頻在這里配置，或者隱藏的照片等等

PHFetchOptions *options = [PHFetchOptions new];
PHFetchResult *topLevelUserCollections = [PHAssetCollection fetchTopLevelUserCollectionsWithOptions:options];
PHAssetCollectionSubtype subType = PHAssetCollectionSubtypeAlbumRegular;
PHFetchResult *smartAlbumsResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum
                                                                                subtype:subType
                                                                                options:options];

3.3 遍歷出需要的相冊(cè)分類

NSMutableArray *photoGroups = [NSMutableArray array];
[topLevelUserCollections enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    if ([obj isKindOfClass:[PHAssetCollection class]]) {
         PHAssetCollection *asset = (PHAssetCollection *)obj;
         PHFetchResult *result = [PHAsset fetchAssetsInAssetCollection:asset options:[PHFetchOptions new]];
         if (result.count > 0) {
             PhotoAssetGroup *g = [PhotoAssetGroup groupWithName:asset.localizedTitle fetchResult:result];
             [photoGroups addObject:g];
         }
     }
}];

[smartAlbumsResult enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    if ([obj isKindOfClass:[PHAssetCollection class]]) {
       PHAssetCollection *asset = (PHAssetCollection *)obj;
       PHFetchOptions *options = [[PHFetchOptions alloc] init];
       options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
            
       PHFetchResult *result = [PHAsset fetchAssetsInAssetCollection:asset options:options];
       if(result.count > 0 && asset.assetCollectionSubtype != PHAssetCollectionSubtypeSmartAlbumVideos) {
           PhotoAssetGroup *g = [PhotoAssetGroup groupWithName:asset.localizedTitle fetchResult:result];
           [photoGroups addObject:g];
        }
     }
}];

3.4 根據(jù)相冊(cè)分類查找所有照片信息

- (NSArray<PhotoAsset *> *)fetchPhotos:(NSArray<PhotoAssetGroup *> *)groups {
    NSMutableArray *photoAssets = [NSMutableArray array];
    for (PhotoAssetGroup *g in groups) {
        __weak typeof(self)weakSelf = self;
        NSIndexSet *indexSet = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, g.result.count)];
        [g.result enumerateObjectsAtIndexes:indexSet options:NSEnumerationReverse usingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
            PHAsset *asset = (PHAsset*)obj;
            if (asset.mediaType == PHAssetMediaTypeImage) {
                if (![weakSelf.imageProcessor checkAlreadyProcessed:asset.localIdentifier]) {
                    PhotoAsset *pAsset = [PhotoAsset assetWthLocaleIdentifier:asset.localIdentifier creationDate:asset.creationDate];
                    if (![photoAssets containsObject:pAsset]) {
                        [photoAssets addObject:pAsset];
                    }
                }
            }
        }];
    }
    
    [photoAssets sortWithOptions:NSSortStable usingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
        PhotoAsset *asset1 = obj1;
        PhotoAsset *asset2 = obj2;
        return ([asset1.creationDate compare:asset2.creationDate] == NSOrderedAscending);
    }];
    return photoAssets;
}

3.5 PhotoAsset和PhotoAssetGroup為自定義類

@interface PhotoAsset : NSObject

@property (nonatomic, copy, readonly) NSString *localIdentifier;
@property (nonatomic, strong) NSDate *creationDate;

- (PhotoAsset *)initWithLocaleIdentifier:(NSString *)identifier creationDate:(NSDate *)date;
+ (PhotoAsset *)assetWthLocaleIdentifier:(NSString *)identifier creationDate:(NSDate *)date;

@end



@interface PhotoAssetGroup : NSObject

@property (nonatomic, copy) NSString *groupName;
@property (nonatomic, strong) PHFetchResult *result;

- (PhotoAssetGroup *)initWithName:(NSString *)name fetchResult:(PHFetchResult *)result;
+ (PhotoAssetGroup *)groupWithName:(NSString *)name fetchResult:(PHFetchResult *)result;

@end
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