Objective-C category "unrecognized selector" error - iphone

Question

I have made a UIImage Objective C catagory to house this function:
#import "UIImage+fixOrientation.h"
#implementation UIImage (fixOrientation)
- (UIImage *)fixOrientation
{
// No-op if the orientation is already correct
if (self.imageOrientation == UIImageOrientationUp) return self;
// We need to calculate the proper transformation to make the image upright.
// We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
CGAffineTransform transform = CGAffineTransformIdentity;
switch (self.imageOrientation) {
case UIImageOrientationDown:
case UIImageOrientationDownMirrored:
transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height);
transform = CGAffineTransformRotate(transform, M_PI);
break;
case UIImageOrientationLeft:
case UIImageOrientationLeftMirrored:
transform = CGAffineTransformTranslate(transform, self.size.width, 0);
transform = CGAffineTransformRotate(transform, M_PI_2);
break;
case UIImageOrientationRight:
case UIImageOrientationRightMirrored:
transform = CGAffineTransformTranslate(transform, 0, self.size.height);
transform = CGAffineTransformRotate(transform, -M_PI_2);
break;
}
switch (self.imageOrientation) {
case UIImageOrientationUpMirrored:
case UIImageOrientationDownMirrored:
transform = CGAffineTransformTranslate(transform, self.size.width, 0);
transform = CGAffineTransformScale(transform, -1, 1);
break;
case UIImageOrientationLeftMirrored:
case UIImageOrientationRightMirrored:
transform = CGAffineTransformTranslate(transform, self.size.height, 0);
transform = CGAffineTransformScale(transform, -1, 1);
break;
}
// Now we draw the underlying CGImage into a new context, applying the transform
// calculated above.
CGContextRef ctx = CGBitmapContextCreate(NULL, self.size.width, self.size.height,
CGImageGetBitsPerComponent(self.CGImage), 0,
CGImageGetColorSpace(self.CGImage),
CGImageGetBitmapInfo(self.CGImage));
CGContextConcatCTM(ctx, transform);
switch (self.imageOrientation) {
case UIImageOrientationLeft:
case UIImageOrientationLeftMirrored:
case UIImageOrientationRight:
case UIImageOrientationRightMirrored:
// Grr...
CGContextDrawImage(ctx, CGRectMake(0,0,self.size.height,self.size.width), self.CGImage);
break;
default:
CGContextDrawImage(ctx, CGRectMake(0,0,self.size.width,self.size.height), self.CGImage);
break;
}
// And now we just create a new UIImage from the drawing context
CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
UIImage *img = [UIImage imageWithCGImage:cgimg];
CGContextRelease(ctx);
CGImageRelease(cgimg);
return img;
}
#end
I've impelmented it to the best of my knowledge but for use reason it keeps coming up with this error:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIImage fixOrientation]: unrecognized selector sent to instance 0x1f0ce270'
in my UIImage+fixOrientation.h file my code looks like this:
#import <UIKit/UIKit.h>
#interface UIImage (fixOrientation)
- (UIImage *)fixOrientation;
#end
and my UIImage+fixOrientation.m file consists of the code I posted at the beginning. I've looked into the other linker flags in the project target build section with some suggestions but this hasn't helped! I honestly cannot figure out why it can't find this function...
Also this is how I've used the function:
NSData *imageData = UIImageJPEGRepresentation([[imageManager pickerImage] fixOrientation], 0.5);
Does anyone have an idea why it might be throwing me this message? Thanks in advance!

Answer 1

Seems like you've simply forgotten to add that category to the target.
Please take a look to that screenshot and check if it looks the same for you:

Answer 2

You will need to add #import UIImage+fixOrientation.h to any file you wish to use the category in. Alternatively, if the method is generally helpful to the whole project, you can put it inside your *-Prefix.pch file so it is available everywhere in the project.