Question

我正在尝试将几张照片（UIImages）合并到图像视图中。我正在使用这种方法：

- (UIImage *) addImageToImage:(UIImage *)img withImage2:(UIImage *)img2{

    CGSize size = CGSizeMake(finalPhoto.image.size.width, finalPhoto.image.size.height);
    UIGraphicsBeginImageContext(size);

    CGPoint pointImg1 = CGPointMake(0,0);
    [img drawAtPoint:pointImg1];

    CGPoint pointImg2 = CGPointMake(0,0);
    [img2 drawAtPoint: pointImg2];

    UIImage* result = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return result;
}

问题是它无法进行合并，因为它没有更正点（我猜......）这是日志：

Jan 17 09:35:20 <Error>: CGContextSaveGState: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextSetBlendMode: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextSetAlpha: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextTranslateCTM: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextScaleCTM: invalid context 0x0
Jan 17 09:35:20  <Error>: CGContextConcatCTM: invalid context 0x0
Jan 17 09:35:20  <Error>: CGContextDrawImage: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextRestoreGState: invalid context 0x0
Jan 17 09:35:20  <Error>: CGContextSaveGState: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextSetBlendMode: invalid context 0x0
Jan 17 09:35:20  <Error>: CGContextSetAlpha: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextTranslateCTM: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextScaleCTM: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextConcatCTM: invalid context 0x0
Jan 17 09:35:20  <Error>: CGContextDrawImage: invalid context 0x0
Jan 17 09:35:20 <Error>: CGContextRestoreGState: invalid context 0x0

这个问题发生在iOS 6和iOS 7上。有没有可行的解决方案？感谢。

Answer 1

使用以下代码：

- (UIImage *) addImageToImage:(UIImage *)img withImage2:(UIImage *)img2{
    //merge two images for this code

    CGSize newSize = CGSizeMake(512,512); // Set your bottom image size
    UIGraphicsBeginImageContext(newSize);

    // Use existing opacity as is
    [img drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];///1st image set frame

    // Apply supplied opacity if applicable
    [img2 drawInRect:CGRectMake(165,332,165,120) blendMode:kCGBlendModeNormal alpha:1];//2nd image set frame with alpha value

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return newImage; //return UIImage
}

Answer 2

我的猜测是你的图像是零指针，所以你用来创建上下文的矩形是空的。在创建上下文之前检查大小的值：

NSLog(@"Size = %@", NSStringFromCGSize(size));

尝试将两个UIImages合并到UIImageView时出错

2 个答案: