来自ALAsset的swift图像

我有通过ALAssetsLibrary从相机返回的图像。现在，我想在UIImageView中显示它。我想这个代码，但它显示了一些错误：来自ALAsset的swift图像

var assets : ALAsset = photoArray.objectAtIndex(indexPath.row) as ALAsset 

cell.cameraOutlet.image = UIImage(CGImage: assets.thumbnail()) as UIImage // Showing error - Missing argument for parameter 'inBundle' in call

在那之后，我尝试这种代码：

var assets : ALAsset = (photoArray.objectAtIndex(indexPath.row) as ALAsset) 
var imageRef : CGImageRef = assets.thumbnail() as CGImageRef // showing error - Unmanaged<CGImage>, is not convertible to CGImageRef 
cell.cameraOutlet.image = UIImage(CGImage: assets.thumbnail()) as UIImage // Showing error - Missing argument for parameter 'inBundle' in call

我想要显示的图像，我该怎么办呢？

dispatch_async(dispatch_get_main_queue(), { 
self.photoLibrary.enumerateGroupsWithTypes(ALAssetsGroupType(ALAssetsGroupAlbum), 
    usingBlock: { 

     (group: ALAssetsGroup!, stop: UnsafePointer<ObjCBool>) -> Void in 
     if group != nil { 
      group.enumerateAssetsUsingBlock({ 
       (asset: ALAsset!, index: Int, stop: UnsafePointer<ObjCBool>) -> Void in 

       if asset != nil 
       { 
        if asset.valueForProperty(ALAssetPropertyType).isEqualToString(ALAssetTypePhoto) 
        { 
         self.photoArray.addObject(asset) 
        } 
       } 
       }) 
     } 
     self.collectionView.reloadData() 
    }, 
    failureBlock: { 
     (myerror: NSError!) -> Void in 
     println("error occurred: \(myerror.localizedDescription)") 
    }) 
    }) 

override func numberOfSectionsInCollectionView(collectionView: UICollectionView!) -> Int { 
     //#warning Incomplete method implementation -- Return the number of sections 
     return photoArray.count 
    } 


    override func collectionView(collectionView: UICollectionView!, numberOfItemsInSection section: Int) -> Int { 
     //#warning Incomplete method implementation -- Return the number of items in the section 
     return 1 
    } 

    override func collectionView(collectionView: UICollectionView!, cellForItemAtIndexPath indexPath: NSIndexPath!) -> UICollectionViewCell! { 
    let cell : CameraCollectionViewCell = collectionView.dequeueReusableCellWithReuseIdentifier("Camera", forIndexPath: indexPath) as CameraCollectionViewCell 

     var asset : ALAsset = photoArray.objectAtIndex(indexPath.row) as ALAsset 
     cell.cameraOutlet.image = UIImage(CGImage: asset.thumbnail().takeUnretainedValue()) as UIImage 
     return cell 
    }

输出结果只显示了一次我认为100次的图像。这个代码有什么问题？

来源

2014-07-26 Alvin Varghese

thumbnail()函数返回Unmanaged<CGImage>。如 Working with Cocoa Data Types中所述，您必须将非托管对象转换为使用takeUnretainedValue()或takeRetainedValue()的内存管理对象。在这种情况下

cell.cameraOutlet.image = UIImage(CGImage: asset.thumbnail().takeUnretainedValue())

因为thumbnail()返回一个不保留对象（是没有“创造”或在其名称中的“复制” ）。

夫特3：

（但是，在资源库框架弃用的iOS 9的和照片的框架应改用）

来源

2014-07-26 10:50:44

我有一个更疑问 –

Hi @Martin，你解释过函数名不包含名称中的“create”或“copy”，所以我们可以推断返回的对象是不存在的。我想知道你是否可以将我指向任何可以进一步阐明这一点的文档？或者，也许我应该使用'takeRetainedValue（）'而不是函数的例子？谢谢！ – ndbroadbent

@ nathan.f77：记载于https://developer.apple.com/library/mac/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html。下面是一个使用takeRetainedValue（）的例子：http://stackoverflow.com/a/26594980/1187415 –

i dislay image use this way: 

let assetslibrary = ZZALAssetsLibrary() 
     assetslibrary.asset(for: imgUrl, 
     resultBlock: { [weak self](mALAsset) in 
      if (mALAsset == nil) { 
       return 
      } 
      //[UIImage imageWithCGImage:resolutionRef scale:1.0f orientation:(UIImageOrientation)representation.orientation]; 
      if let mCGImageVal = mALAsset?.defaultRepresentation().fullScreenImage().takeUnretainedValue() { 
       self?.imageView.image = UIImage(cgImage: mCGImageVal) 
      } 
     }, 
     failureBlock: { (mError) in 
      print("ZZPhotoBrowserCell Photo from asset library error: ",mError ?? "unkown") 
     })

来源

2017-05-31 10:03:30 buoge

来自ALAsset的swift图像

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