得到列表和全尺寸的圖像縮略圖時，點擊列表

Question

的項目所以我用下面的代碼來獲取所有從庫，做工精細的圖像：

func grabPhotos(){ 

    let imgManager = PHImageManager.default() 
    let requestOptions = PHImageRequestOptions() 
    requestOptions.isSynchronous = true 
    requestOptions.deliveryMode = .highQualityFormat 
    let fetchOptions = PHFetchOptions() 
    fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)] 
    if let fetchResults : PHFetchResult = PHAsset.fetchAssets(with: .image, options: fetchOptions){ 

     if fetchResults.count>0{ 

     for i in 0..<fetchResults.count{ 

     imgManager.requestImage(for: fetchResults.object(at: i), targetSize: CGSize(width:100, height: 100), contentMode: .aspectFill, options: requestOptions, resultHandler: { 

     image, error in 
     self.Galleryimages.append(image!) 

     print("array count is ",self.Galleryimages.count) 
     self.photoCollectionview.reloadData() 
     }) 
     } 

    } 
    } 
} 

我顯示所有圖片在我的UICollectionView，但我沒有找到任何方式獲得原始圖像，每當點擊任何縮略圖圖像。當用戶點擊UICollectionView中填充的任何縮略圖圖像時，我想獲取原始圖像（全尺寸圖像）。

謝謝。

Answer 1

要加載縮略圖圖像。

做了太多事情後得到了解決方案，可能是對別人有幫助。以下是執行此操作的步驟。

步驟1：PHFetchResult

的申報對象

var Galleryimages: PHFetchResult<PHAsset>! 

步驟2：

func grabPhotos(){ 

Galleryimages = PHAsset.fetchAssets(with: PHAssetMediaType.image, options: nil) 

}

步驟3：：取使用以下代碼從圖庫結果在您的用戶界面中顯示縮略圖圖像（coll ectionview /泰伯維）使用下面的代碼：

let imageview = cell.viewWithTag(1) as! UIImageView 

PHImageManager.default().requestImage(for: (Galleryimages?[indexPath.row])!, targetSize: CGSize(width: 200, height: 200), contentMode: .aspectFill, options: nil) { (image: UIImage?, info: [AnyHashable: Any]?) -> Void in 
    imageview.image = image 
} 

第4步：，最後用下面的代碼獲取完整大小的圖片。

let options = PHImageRequestOptions() 
options.deliveryMode = .highQualityFormat 
options.resizeMode = .exact 

PHImageManager.default().requestImage(for: (Galleryimages[indexPath.row]), targetSize: PHImageManagerMaximumSize, contentMode: .aspectFill, options: options) { (image: UIImage?, info: [AnyHashable: Any]?) -> Void in 
    if let image = image { 
    //Use this originan image 
    } 
} 

Answer 2

當您從PHAsset中獲取圖像時，您正在調整圖像大小。所以使用

targetsize : PHImageManagerMaximumSize 

從這個U可以得到它的原始大小的原始圖像。併爲你的collectionview你可以direclty從它縮略圖並顯示圖像。所以當用戶點擊縮略圖時，現在你可以顯示原始圖像

請使用autoreleasepool進行內存管理。

for(PHAsset *asset in self.assets) { 
    // This autorelease pool seems good (a1) 
    autoreleasepool { 
     NSLog(@"started requesting image %i", i); 
     [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:PHImageManagerMaximumSize contentMode:PHImageContentModeAspectFit options:[self imageRequestOptions] resultHandler:^(UIImage *image, NSDictionary *info) { 
      dispatch_async(dispatch_get_main_queue(), ^{ 
       //you can add autorelease pool here as well (a2) 
       @autoreleasepool { 
        assetCount++; 
        NSError *error = [info objectForKey:PHImageErrorKey]; 
        if (error) NSLog(@"Image request error: %@",error); 
        else { 
         NSString *imagePath = [appDelegate.docsPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%i.png",i]]; 
         NSData *imageData = UIImagePNGRepresentation(image); 
         if(imageData) { 
          [imageData writeToFile:imagePath atomically:YES]; 
          [self.imagesArray addObject:imagePath]; 
         } 
         else { 
          NSLog(@"Couldn't write image data to file."); 
         } 
         [self checkAddComplete]; 
         NSLog(@"finished requesting image %i", i); 
        } 
       } //a2 ends here 
      }); 
     }]; 
     i++; 
    } // a1 ends here 
}