如何从ios中的URL获取图像大小

Question

如何从objective-C中的URL获取图像的大小(高度/宽度)？我希望我的容器大小根据图像.我正在AFNetworking 3.0. 使用,SDWebImage如果它满足我的要求我可以使用.

Answer 1

在许多情况下,在实际加载图像之前知道图像的大小可能是必要的.例如,在稍后在cellForRowAtIndexPath中加载实际图像时,在heightForRowAtIndexPath方法中设置tableView单元格的高度(这是非常频繁的捕获22).

一种简单的方法是使用Image I/O接口从服务器URL读取映像头:

#import <ImageIO/ImageIO.h>

NSMutableString *imageURL = [NSMutableString stringWithFormat:@"http://www.myimageurl.com/image.png"];

CGImageSourceRef source = CGImageSourceCreateWithURL((CFURLRef)[NSURL URLWithString:imageURL], NULL);
NSDictionary* imageHeader = (__bridge NSDictionary*) CGImageSourceCopyPropertiesAtIndex(source, 0, NULL);
NSLog(@"Image header %@",imageHeader);
NSLog(@"PixelHeight %@",[imageHeader objectForKey:@"PixelHeight"]);

Answer 2

斯威夫特 4.x
Xcode 12.x

func sizeOfImageAt(url: URL) -> CGSize? {
    // with CGImageSource we avoid loading the whole image into memory
    guard let source = CGImageSourceCreateWithURL(url as CFURL, nil) else {
        return nil
    }
    
    let propertiesOptions = [kCGImageSourceShouldCache: false] as CFDictionary
    guard let properties = CGImageSourceCopyPropertiesAtIndex(source, 0, propertiesOptions) as? [CFString: Any] else {
        return nil
    }
    
    if let width = properties[kCGImagePropertyPixelWidth] as? CGFloat,
       let height = properties[kCGImagePropertyPixelHeight] as? CGFloat {
        return CGSize(width: width, height: height)
    } else {
        return nil
    }
}

Answer 3

你可以这样尝试：

NSData *data = [[NSData alloc]initWithContentsOfURL:URL]; 
UIImage *image = [[UIImage alloc]initWithData:data];
CGFloat height = image.size.height;
CGFloat width = image.size.width;