得到列表和全尺寸的图像缩略图时，点击列表

Question

的项目所以我用下面的代码来获取所有从库，做工精细的图像：

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() 
     }) 
     } 

    } 
    } 
} 

我显示所有图片在我的UICollectionView，但我没有找到任何方式获得原始图像，每当点击任何缩略图图像。当用户点击UICollectionView中填充的任何缩略图图像时，我想获取原始图像（全尺寸图像）。

谢谢。

Answer 1

要加载缩略图图像。

做了太多事情后得到了解决方案，可能是对别人有帮助。以下是执行此操作的步骤。

步骤1：PHFetchResult

的申报对象

var Galleryimages: PHFetchResult<PHAsset>! 

步骤2：

func grabPhotos(){ 

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

}

步骤3：：取使用以下代码从图库结果在您的用户界面中显示缩略图图像（coll ectionview /泰伯维）使用下面的代码：

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：，最后用下面的代码获取完整大小的图片。

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

当您从PHAsset中获取图像时，您正在调整图像大小。所以使用

targetsize : PHImageManagerMaximumSize 

从这个U可以得到它的原始大小的原始图像。并为你的collectionview你可以direclty从它缩略图并显示图像。所以当用户点击缩略图时，现在你可以显示原始图像

请使用autoreleasepool进行内存管理。

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 
}