lvterry

// it returns a square thumbnail.

func getAssetThumbnail(asset: PHAsset, size: CGFloat) -> UIImage {
        let retinaScale = UIScreen.mainScreen().scale
        let retinaSquare = CGSizeMake(size * retinaScale, size * retinaScale)
        let cropSizeLength = min(asset.pixelWidth, asset.pixelHeight)
        let square = CGRectMake(0, 0, CGFloat(cropSizeLength), CGFloat(cropSizeLength))
        let cropRect = CGRectApplyAffineTransform(square, CGAffineTransformMakeScale(1.0/CGFloat(asset.pixelWidth), 1.0/CGFloat(asset.pixelHeight)))
        
        let manager = PHImageManager.defaultManager()