UIImage转NSData有时为nil

一般, 我们会用UIImagePNGRepresentation, UIImagePNGRepresentation来达到目的, 但有时候, 发现它的返回值为nil...

不需要怀疑这么简单处理有什么问题, 文档 就是如此:

Return Value

A data object containing the PNG data, or nil if there was a problem generating the data. This function may return nil if the image has no data or if the underlying CGImageRef contains data in an unsupported bitmap format.

也就是说, 没有data的情况还是挺多的, 我们还是放弃这个方法吧, 换别的吧, 提供三种思路

复制一张图片

var imageName: String = "MyImageName.png"
var image = UIImage(named: imageName)
var rep = UIImagePNGRepresentation(image)

当然, 这不能保证什么

重绘一张图片

UIGraphicsBeginImageContext(originalImage.size);
[originalImage drawInRect:CGRectMake(0, 0, originalImage.size.width, originalImage.size.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

或

UIGraphicsBeginImageContext(CGSizeMake(1, 1))
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

不用 UIImage

1和2都没验证过, 但都是在StackOverflow上别人贴出的答案, 我之所以不验证了, 因为我是这么做的

CGDataProviderRef provider = CGImageGetDataProvider(image.CGImage);
NSData* data = (id)CFBridgingRelease(CGDataProviderCopyData(provider));

通了就没动力继续试啦, 而且本身已经很简洁了, 此外方法名也非常直白"DataProvider", 还想怎样!