Objective-C versus C#, part 2: Loading, rotating, and saving an image

 

In this example, I’ll compare Objective-C/Cocoa Touch to C#/.NET in their ability to load an image from a file, rotate it 90 degrees, and then save the modified image.  Both platforms are perfectly capable of performing this task.  One of them, however, sucks orders of magnitude less.  I’ll leave it as an exercise to the reader to decide to which I’m referring.  I’ll list the C# example first this time, since I wouldn’t want to be accused of favoritism.  In fairness, I should point out that for the Objective-C version, I cut some corners.  By using a UIImageView to house the image, I saved many lines of code that would result from applying transforms to the graphics context directly.

C#/.NET

Image myImage = Image.FromFile(@"c:\myImage.png");
myImage.RotateFlip(RotateFlipType.Rotate90FlipNone);
myImage.Save(@"c:\newImage.png");

Objective-C/Cocoa Touch

UIImage* myImage = [UIImage imageNamed:@"myImage.png"];
UIImageView* imageView = [[UIImageView alloc] initWithImage:myImage];
[imageView setTransform:CGAffineTransformMakeRotation(M_PI / 2.0)];
	
CGSize newImageSize = CGSizeMake(myImage.size.y, myImage.size.x);
UIGraphicsBeginImageContext(newImageSize);
[imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage* newImage = [UIGraphicsGetImageFromCurrentImageContext() retain];
UIGraphicsEndImageContext();
	
[UIImagePNGRepresentation(newImage) writeToFile:@"myNewImage.png" atomically:YES];

[imageView release];
[newImage release];