[iOS] 视图截屏

+ (UIImage *)lj_snapshot:(UIView *)view {
    
    if (!view) {
        view = [UIApplication sharedApplication].keyWindow;
    }
    
    CGSize size = view.bounds.size;
    
    UIGraphicsBeginImageContextWithOptions(size, NO, [UIScreen mainScreen].scale);
    
    CGRect rec = CGRectMake(view.frame.origin.x, view.frame.origin.y, view.bounds.size.width, view.bounds.size.height);
    
    [view drawViewHierarchyInRect:rec afterScreenUpdates:YES];
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return image;
}