如何正確裁剪UIImage與UIImagePickerController？

這是攝像頭的覆蓋我的應用程序，如何正確裁剪UIImage與UIImagePickerController？

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黃方是表明，只有這一部分（攝像頭）裏面的照片將被保存用戶。這就像莊稼。

當我保存的捕獲映像，它可以節省縮放照片[大變焦的圖片]，

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我發現了什麼，當我拍了一張照片，這將是的的{2448, 3264}

我裁剪這樣的圖像大小，

- (UIImage *)imageByCroppingImage:(UIImage *)image toSize:(CGSize)size 
{ 
    double x = (image.size.width - size.width)/2.0; 
    double y = (image.size.height - size.height)/2.0; 

    CGRect cropRect = CGRectMake(x, y, size.height, size.width); 
    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], cropRect); 

    UIImage *cropped = [UIImage imageWithCGImage:imageRef]; 
    CGImageRelease(imageRef); 

    return cropped; 
} 

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info 
{ 
    UIImage *image = [info valueForKey:UIImagePickerControllerOriginalImage]; 

    if (image) { 
     UIImage *newImage = [self imageByCroppingImage:image toSize:CGSizeMake(300.f, 300.f)]; 
     UIImageWriteToSavedPhotosAlbum(newImage, nil, nil, nil); 
    } 
}

注意，

在裁剪之前修正了方向。使用這個，http://pastebin.com/WYUkDLS0
相機上的黃色正方形也是相同的大小，寬度= 300和高度= 300。
如果我將前置攝像頭設置爲UIImagePickerController那麼它會給我完美的裁剪圖像輸出。 是的，這真的很奇怪！
我試過了這裏的一切，Cropping an UIImage。即使https://github.com/Nyx0uf/NYXImagesKit也無濟於事。

任何想法/建議嗎？

更新：

從這個問題，Trying to crop my UIImage to a 1:1 aspect ratio (square) but it keeps enlarging the image causing it to be blurry. Why?

我也跟着這樣@DrummerB的答案，

CGFloat originalWidth = image.size.width * image.scale; 
    CGFloat originalHeight = image.size.height * image.scale; 
    float smallestDimension = fminf(originalWidth, originalHeight); 
    CGRect square = CGRectMake(0, 0, smallestDimension, smallestDimension); 
    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], square); 
    UIImage *squareImage = [UIImage imageWithCGImage:imageRef scale:image.scale orientation:image.imageOrientation]; 
    UIImageWriteToSavedPhotosAlbum(squareImage, nil, nil, nil); 
    CGImageRelease(imageRef);

這是我拍攝的，

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