最近一直在开发ipad App，关于照片这块遇到一个问题：在横屏模式下（向右横屏，Home键在左边），调用系统相机，拍照后 返回的照片 被旋转了180度，感觉也是莫名其妙，iPhone 上就没有这个问题。上网搜索，还真有类似的问题，也有解决办法。下边 贴上代码：

创建一个UIImage的分类，我命名为FixOrientation：

.h文件：

#import@interface UIImage (FixOrientation)

-(UIImage*)fixOrientation:(UIImage *)aImage;

@end

.m文件 ：

#import "UIImage+FixOrientation.h"

@implementation UIImage (FixOrientation)

-(UIImage*)fixOrientation:(UIImage*)aImage {

// No-op if the orientation is already correct

if (aImage.imageOrientation == UIImageOrientationUp)

return aImage;

// 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 (aImage.imageOrientation) {

case UIImageOrientationDown:

case UIImageOrientationDownMirrored:

transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);

transform = CGAffineTransformRotate(transform, M_PI);

break;

case UIImageOrientationLeft:

case UIImageOrientationLeftMirrored:

transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);

transform = CGAffineTransformRotate(transform, M_PI_2);

break;

case UIImageOrientationRight:

case UIImageOrientationRightMirrored:

transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);

transform = CGAffineTransformRotate(transform, -M_PI_2);

break;

default:

break;

}

switch (aImage.imageOrientation) {

case UIImageOrientationUpMirrored:

case UIImageOrientationDownMirrored:

transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);

transform = CGAffineTransformScale(transform, -1, 1);

break;

case UIImageOrientationLeftMirrored:

case UIImageOrientationRightMirrored:

transform = CGAffineTransformTranslate(transform, aImage.size.height, 0);

transform = CGAffineTransformScale(transform, -1, 1);

break;

default:

break;

}

// Now we draw the underlying CGImage into a new context, applying the transform

// calculated above.

CGContextRef ctx = CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height,

CGImageGetBitsPerComponent(aImage.CGImage), 0,

CGImageGetColorSpace(aImage.CGImage),

CGImageGetBitmapInfo(aImage.CGImage));

CGContextConcatCTM(ctx, transform);

switch (aImage.imageOrientation) {

case UIImageOrientationLeft:

case UIImageOrientationLeftMirrored:

case UIImageOrientationRight:

case UIImageOrientationRightMirrored:

// Grr...

CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage);

break;

default:

CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.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

然后在 选择照片后的回调方法中 调用此方法就可以了。