指定从NSData加载的UIImage的比例

Question

My app stores images as NSData objects. However, when these are loaded on an iPhone 4, they are displayed at double the size because the default scale factor is 1. I have 2 questions I would appreciate help with please:

1. Is there any way to set the scale of the UIImage without using initWithCGImage:scale:orientation:

2. If the answer to 1 is no, what is the most efficient way to load the NSData into a UIImage using the method above? At present it seems I will have to create a UIImage from the NSData and then create another UIImage using the method noted in 1 above.

Thank you.

Answer 1

1. UIImage is immutable, so I guess there is no way to do so without hacking.
2. UIImage is just a wrapper of CGImage , so I think using initWithCGImage: as you describe won't have any noticeable performance impact. If you really worry about that, you can load it to CGImageRef first.