spin-docta spin-docta - 3 months ago 13
Objective-C Question

Objective-C Category Causing unrecognized selector

My project has a UIImage category function that I want to call from another class. I properly import the header file for the image category and I get the project to compile with no warning.

The problem is that when I call the uiimage category function I seen an unrecognized selector error with a NSInvalidArgumentException. Why am I seeing this if I've properly linked everything?

#import <UIKit/UIKit.h>

@interface UIImage (DRShare)

+ (UIImage*) imageNamed:(NSString*)name;

@end


@implementation UIImage (DRShare)

+ (UIImage*) imageNamedDR:(NSString*)name{

CGFloat s = 1.0f;
if([[UIScreen mainScreen] respondsToSelector:@selector(scale)]){
s = [[UIScreen mainScreen] scale];
}

NSString *path = [NSString stringWithFormat:@"%@%@%@.png",kImagesPath,name,s > 1 ? @"@2x":@""];
return [UIImage imageWithContentsOfFile:DRBUNDLE(path)];
}

@end


file that calls it:

backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamedDR:@"Share Popup Background"]];


exception raised:

2010-10-22 11:51:02.880 Stuff[11432:207] +[UIImage imageNamedDR:]: unrecognized selector sent to class 0x1f8e938
2010-10-22 11:51:02.883 Stuff[11432:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[UIImage imageNamedDR:]: unrecognized selector sent to class 0x1f8e938'
*** Call stack at first throw:
(
0 CoreFoundation 0x02e65b99 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x02fb540e objc_exception_throw + 47
2 CoreFoundation 0x02e6776b +[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x02dd72b6 ___forwarding___ + 966
4 CoreFoundation 0x02dd6e72 _CF_forwarding_prep_0 + 50
5 TapTapShare 0x0001291c -[DRShareViewController backgroundView] + 127
6 TapTapShare 0x00012343 -[DRShareViewController loadView] + 639
7 UIKit 0x0044f54f -[UIViewController view] + 56
8 UIKit 0x0044d9f4 -[UIViewController contentScrollView] + 42
9 UIKit 0x0045d7e2 -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 48
10 UIKit 0x0045bea3 -[UINavigationController _layoutViewController:] + 43
11 UIKit 0x0045d12d -[UINavigationController _startTransition:fromViewController:toViewController:] + 524
12 UIKit 0x00457ccd -[UINavigationController _startDeferredTransitionIfNeeded] + 266
13 UIKit 0x00574b55 -[UILayoutContainerView layoutSubviews] + 226
14 QuartzCore 0x02616481 -[CALayer layoutSublayers] + 177
15 QuartzCore 0x026161b1 CALayerLayoutIfNeeded + 220
16 QuartzCore 0x026160bd -[CALayer layoutIfNeeded] + 111

Answer

A couple possibilities:

  1. You did not link UIImage+TTShare.m into your target. So while you have the header, you're not compiling the implementation.
  2. If this is part of a static library, you need to add -all_load to the Other Linker Flags build setting for the app linking against the library.
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