drawinrect绘制图片

- (UIImage *) photoMerge:(UIImage*)leftImage1 :(UIImage*)rightImage1 :(UIImage*)leftImage2 :(UIImage*)rightImage2
{
CGFloat width = 1000;//最终合并后图片 宽度
CGFloat height = 1000;//最终合并后图片 高度

CGSize offScreenSize = CGSizeMake(width, height);
UIGraphicsBeginImageContext(offScreenSize);

//左上
CGRect rect = CGRectMake(0, 0, width/2, height/2);
[leftImage1 drawInRect:rect];


//右上
rect.origin.x += width/2;
[rightImage1 drawInRect:rect];


//左下
CGRect rect2 = CGRectMake(0, height/2, width/2, height/2);
[leftImage2 drawInRect:rect2];


//右下
rect2.origin.x += width/2;
[rightImage2 drawInRect:rect2];


UIImage* imagez = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return imagez;
}