在iPhone中将两个图像合并为一个图像

Question

我需要将两张图片合并成一张图片，下面是我的代码：

-(UIImage*)mergeImage:(UIImage*)mask overImage:(UIImage*)source inSize:(CGSize)size
{
    //Capture image context ref

    UIImageView *totalimage=[[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];

    UIImageView *firstImage=[[UIImageView alloc] initWithImage:mask];
    UIImageView *secondImage=[[UIImageView alloc] initWithImage:source];

    [totalimage addSubview:firstImage];
    [totalimage addSubview:secondImage];

    UIGraphicsBeginImageContext(totalimage.bounds.size);
    [totalimage.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    //Draw images onto the context
    [source drawInRect:CGRectMake(0, 0, source.size.width, source.size.height)]; 
    [mask drawInRect:CGRectMake(0, 0, mask.size.width, mask.size.height)]; 

    return viewImage;

}

我按如下方式调用此方法：

UIImage *totalImage = [self mergeImage:self.Apicimage overImage:questionImage inSize:CGSizeMake(100, 100)];

但在执行时，我会得到以下输出：

Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextSaveGState: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextSetBlendMode: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextSetAlpha: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextTranslateCTM: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextScaleCTM: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextConcatCTM: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextDrawImage: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextRestoreGState: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextSaveGState: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextSetBlendMode: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextSetAlpha: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextTranslateCTM: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextScaleCTM: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextConcatCTM: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextDrawImage: invalid context 0x0
Jun 15 16:11:06 iPad-2 VueGuides[9195] <Error>: CGContextRestoreGState: invalid context 0x0

有谁能给我指路吗？如何合并两个图像？

Answer 1

你的代码

[source drawInRect:CGRectMake(0, 0, source.size.width, source.size.height)]; 
    [mask drawInRect:CGRectMake(0, 0, mask.size.width, mask.size.height)]; 

应该在此之前编写

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