屏幕截图的方法

不用 2d截图   直接截图

-(UIImage *)screenShots
{
     //截取整个backview
    UIGraphicsBeginImageContext(self.backgroundView.bounds.size);
    [self.backgroundView.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *sourceImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

//在截图上画下自己需要的位置及大小
    UIGraphicsBeginImageContext(self.mainContentView.frame.size);
    [sourceImage drawAtPoint:CGPointMake(0, self.mainContentView.bounds.size.height - self.view.bounds.size.height)];13     UIImage * image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsGetCurrentContext();

       return image;
}