从iPhone中的UIImagePickerController存储图像？

Question

我尝试在iPhone中存储来自NSUserDefault的图片（UIImagePickerController）。

这种方式存储图像：

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    UIImage *originalImage=[info objectForKey:UIImagePickerControllerOriginalImage];
    NSData * imageData = UIImagePNGRepresentation(originalImage);
    NSUserDefaults *user = [NSUserDefaults standardUserDefaults];
    [user setValue:imageData forKey:@"pictureData"];
}

这种检索图像的方式：

NSUserDefaults *user = [NSUserDefaults standardUserDefaults];
UIImage *myImage = [UIImage imageWithData:[user valueForKey:@"pictureData"]];
[btn2 setImage:myImage forState:UIControlStateNormal];

当我从NSUserDefaults检索图像到设置UIButton时，最后显示的图像，但方向从下向右变化，如何解决此问题？请帮帮我

Answer 1

UIImage有一个属性imageOrientation，指示UIImageView和其他UIImage消费者旋转原始图像数据。这个标志很有可能被保存到上传的jpeg图像中的exif数据中，但是用来查看它的程序并没有尊重那个标志。

要轮播UIImage以便在上传时正确显示，您可以使用以下类别：

<强>的UIImage + fixOrientation.h

@interface UIImage (fixOrientation)

 - (UIImage *)fixOrientation;

@end

<强>的UIImage + fixOrientation.m

@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;
    case UIImageOrientationUp:
    case UIImageOrientationUpMirrored:
        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;
    case UIImageOrientationUp:
    case UIImageOrientationDown:
    case UIImageOrientationLeft:
    case UIImageOrientationRight:
        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

Answer 2

使用UIImageJPEGRepresentation以这种方式将图像存储到NSUserDefaults：

NSData * imageData = UIImageJPEGRepresentation(originalImage, 90);
NSUserDefaults *user = [NSUserDefaults standardUserDefaults];
[user setValue:imageData forKey:@"pictureData"];