scrollView截取指定区域的图片

把scrollView放到一个容器里面，再截图就可以了

scrollview放到容器：

    UIView *lunboCarrier = [[UIView alloc] initWithFrame:CGRectMake(0, CGRectGetMaxY(self.headerLevelView.frame) + widthWith6(24), Main_Screen_Width, widthWith6(170))];
    [self.headerV addSubview:lunboCarrier];
    lunboCarrier.backgroundColor = [UIColor clearColor];
    _lunboView = [[GXLunBoView alloc] initWithFrame:lunboCarrier.bounds]; // GXLunBoView是轮播图

截图：

+(UIImage*)imageFromView:(UIView *)theView atFrame:(CGRect)rect {
    
    UIGraphicsBeginImageContext(theView.frame.size);
    
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    CGContextSaveGState(context);
    
    UIRectClip(rect);
    
    [theView.layer renderInContext:context];
    
    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return  theImage;
    
}