两张图片合并
-(UIImage *)addImage:(UIImage *)p_w_picpath1 toImage:(UIImage *)p_w_picpath2
{


    UIGraphicsBeginImageContext(p_w_picpath2.size);
    
    //Draw p_w_picpath2
    [p_w_picpath2 drawInRect:CGRectMake(0, 0, p_w_picpath2.size.width, p_w_picpath2.size.height)];
    
    //Draw p_w_picpath1
    [p_w_picpath1 drawInRect:CGRectMake(20, 20, p_w_picpath1.size.width, p_w_picpath1.size.height)];
    
    UIImage *resultImage=UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return resultImage;
}

截图
- (UIImage*) combineImageFromCuttingScreen {


    
    UIGraphicsBeginImageContext(self.baseImageView.frame.size);  
    UIGraphicsBeginImageContextWithOptions(self.combineView.frame.size, YES, 1);
    CGContextRef context = UIGraphicsGetCurrentContext();  
    CGContextSetShouldAntialias(context, YES);
    CGContextSetShouldSmoothFonts(UIGraphicsGetCurrentContext(),YES);
    CGContextSaveGState(context);  
    CGRect r = CGRectMake(0, 0, 320, 392);
    UIRectClip(r);  
    [self.combineView.layer renderInContext:context];  
    
    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();  
    UIGraphicsEndImageContext();  
    
    return  theImage;
}