How to get Image size from URL in ios - objective-c

Question

How can I get the size(height/width) of an image from URL in objective-C? I want my container size according to the image. I am using AFNetworking 3.0.
I could use SDWebImage if it fulfills my requirement.

Answer 1

Knowing the size of an image before actually loading it can be necessary in a number of cases. For example, setting the height of a tableView cell in the heightForRowAtIndexPath method while loading the actual image later in the cellForRowAtIndexPath (this is a very frequent catch 22).
One simple way to do it, is to read the image header from the server URL using the Image I/O interface:
#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

Swift 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

Use Asynchronous mechanism called GCD in iOS to dowload image without affecting your main thread.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Download IMAGE using URL
NSData *data = [[NSData alloc]initWithContentsOfURL:URL];
// COMPOSE IMAGE FROM NSData
UIImage *image = [[UIImage alloc]initWithData:data];
dispatch_async(dispatch_get_main_queue(), ^{
// UI UPDATION ON MAIN THREAD
// Calcualte height & width of image
CGFloat height = image.size.height;
CGFloat width = image.size.width;
});
});

Answer 4

For Swift 4 use this:
let imageURL = URL(string: post.imageBigPath)!
let source = CGImageSourceCreateWithURL(imageURL as CFURL,
let imageHeader = CGImageSourceCopyPropertiesAtIndex(source!, 0, nil)! as NSDictionary;
print("Image header: \(imageHeader)")
The header would looks like:
Image header: {
ColorModel = RGB;
Depth = 8;
PixelHeight = 640;
PixelWidth = 640;
"{Exif}" = {
PixelXDimension = 360;
PixelYDimension = 360;
};
"{JFIF}" = {
DensityUnit = 0;
JFIFVersion = (
1,
0,
1
);
XDensity = 72;
YDensity = 72;
};
"{TIFF}" = {
Orientation = 0;
}; }
So u can get from it the Width, Height.

Answer 5

you can try like this:
NSData *data = [[NSData alloc]initWithContentsOfURL:URL];
UIImage *image = [[UIImage alloc]initWithData:data];
CGFloat height = image.size.height;
CGFloat width = image.size.width;