Objective-C类“无法识别的选择器”错误

Question

我已经制作了一个UIImage Objective C类别来容纳此功能：

    #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

据我所知，我已将其实施，但由于使用原因，它不断出现此错误：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIImage fixOrientation]: unrecognized selector sent to instance 0x1f0ce270'

在我的UIImage + fixOrientation.h文件中，我的代码如下所示：

#import <UIKit/UIKit.h>

@interface UIImage (fixOrientation)

- (UIImage *)fixOrientation;


@end

我的UIImage + fixOrientation.m文件由我一开始发布的代码组成。 我已经在项目目标构建部分中研究了其他链接器标志 ，并提供了一些建议，但这没有帮助！ 老实说，我无法弄清楚为什么找不到此功能...

这也是我使用函数的方式：

NSData *imageData = UIImageJPEGRepresentation([[imageManager pickerImage] fixOrientation], 0.5);

有谁知道为什么它会向我抛出此消息？ 提前致谢！

Answer 1

似乎您只是忘记了将该类别添加到目标中。

请查看该屏幕截图，并检查它是否与您相同：

Answer 2

您将需要将#import UIImage+fixOrientation.h添加到希望使用该类别的任何文件中。或者，如果该方法通常对整个项目有用，则可以将其放在*-Prefix.pch文件中，以便在项目的任何地方都可用。