iOS中獲取系統(tǒng)相冊(cè)中的圖片

一、調(diào)起系統(tǒng)相冊(cè)選擇器

  • 1.利用UIImagePickerController從系統(tǒng)自帶的App(照片\相機(jī))中獲得圖片
  • 2.設(shè)置代理,遵守代理協(xié)議

注意這個(gè)UIImagePickerController類比較特殊,需要遵守兩個(gè)代理協(xié)議

@interface ViewController () <UIImagePickerControllerDelegate, UINavigationControllerDelegate>

  • 3.實(shí)現(xiàn)代理的方法didFinishPickingMediaWithInfo

-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info

-(void)showActionSheet
{
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"選擇圖片" message:nil preferredStyle:UIAlertControllerStyleActionSheet];
    UIAlertAction *action1 = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];
    UIAlertAction *action2 = [UIAlertAction actionWithTitle:@"拍照" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        NSString *mediaType = AVMediaTypeVideo;
        AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType];
        if(authStatus == AVAuthorizationStatusRestricted || authStatus == AVAuthorizationStatusDenied){
            //            mAlertView(@"", @"請(qǐng)?jiān)?設(shè)置'中打開相機(jī)權(quán)限")
            return;
        }
        
        if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
            //            mAlertView(@"", @"照相機(jī)不可用")
            return;
        }
        UIImagePickerController *vc = [[UIImagePickerController alloc] init];
        vc.delegate = self;
        vc.allowsEditing = YES;
        vc.sourceType = UIImagePickerControllerSourceTypeCamera;
        [self presentViewController:vc animated:YES completion:nil];
    }];
    UIAlertAction *action3 = [UIAlertAction actionWithTitle:@"相冊(cè)選擇" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        UIImagePickerController *vc = [[UIImagePickerController alloc] init];
        vc.delegate = self;
        vc.allowsEditing = YES;
        vc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        [self presentViewController:vc animated:YES completion:nil];
    }];
    [alert addAction:action1];
    [alert addAction:action2];
    [alert addAction:action3];
    [self presentViewController:alert animated:YES completion:nil];
}

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

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
{
    UIImage *image = [info objectForKey:UIImagePickerControllerEditedImage];
    [self.senderBtn setBackgroundImage:image forState:UIControlStateNormal];
    //圖片在這里壓縮一下
    NSData *imageData = UIImageJPEGRepresentation(image, 0.5f);
    if (imageData.length/1024 > 1024*20)
    {
//        mAlertView(@"溫馨提示", @"請(qǐng)重新選擇一張不超過(guò)20M的圖片");
    }
    else
    {
//        _imageType = [NSData typeForImageData:imageData];
//        _imageBase64 = [imageData base64EncodedString];
    }
    [picker dismissViewControllerAnimated:YES completion:nil];

}

二、獲取系統(tǒng)相冊(cè)所有圖片

  • 導(dǎo)入頭文件#import <Photos/Photos.h>
  • PHAsset : 一個(gè)資源, 比如一張圖片\一段視頻
  • PHAssetCollection : 一個(gè)相簿
  • PHImageManager 圖片管理者,是單例,發(fā)送請(qǐng)求才能從asset獲取圖片
  • PHImageRequestOptions圖片請(qǐng)求選項(xiàng)

注意:這個(gè)類是iOS8開始推廣,iOS9開始廢棄之前的方法
系統(tǒng)適配iOS8之前,用下面這個(gè)庫(kù)里面的API
import <AssetsLibrary/AssetsLibrary.h>

  • 1.獲得相簿全部原圖
- (void)getOriginalImages
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // 獲得所有的自定義相簿
        PHFetchResult<PHAssetCollection *> *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
        // 遍歷所有的自定義相簿
        for (PHAssetCollection *assetCollection in assetCollections) {
            [self enumerateAssetsInAssetCollection:assetCollection original:YES];
        }
        
        // 獲得相機(jī)膠卷
        PHAssetCollection *cameraRoll = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil].lastObject;
        // 遍歷相機(jī)膠卷,獲取大圖
        [self enumerateAssetsInAssetCollection:cameraRoll original:YES];
    });
}
  • 2.獲得相簿中全部縮略圖
- (void)getThumbnailImages
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // 獲得所有的自定義相簿
        PHFetchResult<PHAssetCollection *> *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
        // 遍歷所有的自定義相簿
        for (PHAssetCollection *assetCollection in assetCollections) {
            [self enumerateAssetsInAssetCollection:assetCollection original:NO];
        }
        // 獲得相機(jī)膠卷
        PHAssetCollection *cameraRoll = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil].lastObject;
        [self enumerateAssetsInAssetCollection:cameraRoll original:NO];
    });
}
  • 3.遍歷相冊(cè)
 *  遍歷相簿中的全部圖片
 *  @param assetCollection 相簿
 *  @param original        是否要原圖
 */
- (void)enumerateAssetsInAssetCollection:(PHAssetCollection *)assetCollection original:(BOOL)original
{
    NSLog(@"相簿名:%@", assetCollection.localizedTitle);
    
    PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
    options.resizeMode = PHImageRequestOptionsResizeModeFast;
    // 同步獲得圖片, 只會(huì)返回1張圖片
    options.synchronous = YES;
    
    // 獲得某個(gè)相簿中的所有PHAsset對(duì)象
    PHFetchResult<PHAsset *> *assets = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];
    for (PHAsset *asset in assets) {
        // 是否要原圖
        CGSize size = original ? CGSizeMake(asset.pixelWidth, asset.pixelHeight) : CGSizeZero;
        
        // 從asset中獲得圖片
        __weak typeof(self) weakSelf = self;
        [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
            NSLog(@"%@", result);
            original ? [weakSelf.photoArray addObject:result] : [weakSelf.photoArray addObject:result];
        }];
        dispatch_async(dispatch_get_main_queue(), ^{
            [weakSelf.showPhotoCollectionView reloadData];
        });
    }
}

特別注意：
(1).獲取全部原圖或者全部縮略圖時(shí)，運(yùn)行的代碼要放在 全局并行隊(duì)列中


910C933E-8719-4ABD-A24B-547129ED7F7A.png

(2).遍歷相冊(cè)獲取到所有圖片后再主線程中刷新列表


419D68CD-976F-4F16-B09F-9130240FAF95.png

(3).經(jīng)過(guò)本人測(cè)試，放在全局并行隊(duì)列之后獲取相冊(cè)圖片速度都是秒級(jí)可以完成，不會(huì)阻塞主線程。

上面的Demo鏈接

這個(gè)簡(jiǎn)單的需求是因?yàn)轫?xiàng)目中只要選擇一張圖片，并且不需要展現(xiàn)圖片詳情，直接選擇，后續(xù)會(huì)補(bǔ)上多張圖片選擇、展示的事例。

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