如何在IOS 8中自定义UIAlertController按钮标题的字体大小

Question

如何在IOS 8中使用UIActionSheet样式更改UIAlertController按钮标题的字体大小。

我尝试过以下功能，但这对IOS8无效。

- (void)willPresentActionSheet:(UIActionSheet *)actionSheet {
    for (UIView *_currentView in actionSheet.subviews) {
        if ([_currentView isKindOfClass:[UILabel class]]) {
            UILabel *l = [[UILabel alloc] initWithFrame:_currentView.frame];
            l.text = [(UILabel *)_currentView text];
            [l setFont:[UIFont fontWithName:@"Arial-BoldMT" size:20]];
            [actionSheet addSubview:l];
            _currentView.hidden = YES;
            break;
        }
    }
}