Alvin Varghese Alvin Varghese - 1 month ago 18
Swift Question

image from ALAsset in swift

I have images that returned from the camera by the ALAssetsLibrary. Now, I want to display it in a

UIImageView
. I tried this code, but it shows some errors:

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


after that, I tried this code:

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


I want to display the image, how can I do this?

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
}


The output shows only one image for a 100 time I think. Whats the problem with this code?

Answer

The thumbnail() function returns Unmanaged<CGImage>. As explained in Working with Cocoa Data Types, you have to convert the unmanaged object to a memory managed object with takeUnretainedValue() or takeRetainedValue(). In this case

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

because thumbnail() returns an unretained object (is does not have "create" or "copy" in its name).

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