iOS 获取网络图片的大小

一直都在找关于获取网络图片的大小的方法， 今天找到了一个能解决的办法 ，如下

1， 导入框架

 #import <ImageIO/ImageIO.h>

2. 使用此方法得到image的size

- (CGSize)getImageSizeWithURL:(NSURL *)url
{
    CGImageSourceRef imageSource = CGImageSourceCreateWithURL((CFURLRef)url, NULL);
    CGFloat width = 0.0f, height = 0.0f;

    if (imageSource)
    {
        CFDictionaryRef imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, , NULL);

        if (imageProperties != NULL)
        {
            CFNumberRef widthNum  = CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelWidth);
            if (widthNum != NULL) {
                CFNumberGetValue(widthNum, kCFNumberFloatType, &width);
            }

            CFNumberRef heightNum = CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelHeight);
            if (heightNum != NULL) {
                CFNumberGetValue(heightNum, kCFNumberFloatType, &height);
            }

            CFRelease(imageProperties);
        }
        CFRelease(imageSource);
        NSLog(@"Image dimensions: %.0f x %.0f px", width, height);
    }
    return CGSizeMake(width, height);
}