全屏图：

-(void)fullScreenshots{
 
UIWindow *screenWindow = [[UIApplication sharedApplication] keyWindow];
 
    UIGraphicsBeginImageContext(screenWindow.frame.size);//全屏截图，包括window
 
    [screenWindow.layer renderInContext:UIGraphicsGetCurrentContext()];
 
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
 
    UIGraphicsEndImageContext();
 
    UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
 
}

截取自定义的大小

iPhone开发应用中抓图程序案例实现是本文要介绍的内容，主要是通过代码来实现抓图程序，具体实现过程，一起来看详细代码。
 
    //获得屏幕图像  
    - (UIImage *)imageFromView: (UIView *) theView    
    {  
          
        UIGraphicsBeginImageContext(theView.frame.size);  
        CGContextRef context = UIGraphicsGetCurrentContext();  
        [theView.layer renderInContext:context];  
        UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();  
        UIGraphicsEndImageContext();  
          
        return theImage;  
    }  
     
    //获得某个范围内的屏幕图像  
    - (UIImage *)imageFromView: (UIView *) theView   atFrame:(CGRect)r  
    {  
        UIGraphicsBeginImageContext(theView.frame.size);  
        CGContextRef context = UIGraphicsGetCurrentContext();  
        CGContextSaveGState(context);  
        UIRectClip(r);  
        [theView.layer renderInContext:context];  
        UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();  
        UIGraphicsEndImageContext();  
          
        return  theImage;//[self getImageAreaFromImage:theImage atFrame:r];  
    }

//保存图片到本地

//保存图片到本地
- (void)saveImageToPhotos:(UIImage*)savedImage

{
    
    UIImageWriteToSavedPhotosAlbum(savedImage, self, @selector(image:didFinishSavingWithError:contextInfo:), NULL);
    
}
// 指定回调方法
- (void)image: (UIImage *) image didFinishSavingWithError: (NSError *) error contextInfo: (void *) contextInfo
{
    
    NSString *msg = nil ;
    
    if(error != NULL){
        
        msg = @"保存失败!" ;
        
    }else{
        
        msg = @"保存成功!" ;
        
    }
    
    [MBProgressHUD showError:msg toView:self.view];
}

关于直播间截屏 比较特殊。
目前多数的直播播放是使用openGLES来实现的，使用常用的

UIWindow *mainWindow = [UIApplication sharedApplication].keyWindow;
   CGContextRef context = UIGraphicsGetCurrentContext();
   CGContextFillRect(context, bounds);
   CGContextTranslateCTM(context, shrinkSize.width, shrinkSize.height);
   [mainWindow.layer renderInContext:context];
   UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

不能截取播放器播放的画面，只能截取到一块黑屏
目前使用下面的方法可以直接截取

    UIWindow *mainWindow = [UIApplication sharedApplication].keyWindow;
    UIGraphicsBeginImageContextWithOptions(mainWindow.frame.size, NO, 0);
    [mainWindow drawViewHierarchyInRect:mainWindow.frame afterScreenUpdates:YES];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();