我如何以编程方式将UILabel居中于UIView？

Question

我经历了这个话题，几乎对每个建议都进行了尝试，但是我的标签仍然拒绝在view中居中：

How to center a UILabel on UIView

这是我得到的最接近的：

[我首先想到的是view隐藏在tab bar下，但根据debug hierarchy，view恰好在tab bar开始的位置结束。

代码看起来像这样：

    _noExperiences = [[UIView alloc] initWithFrame:self.view.frame];
    _noExperiences.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:_noExperiences];

    UILabel *nothingToShow = [[UILabel alloc] initWithFrame:CGRectMake(_noExperiences.center.x, _noExperiences.center.y, 200, 20)];
    nothingToShow.text = @"HELLO";
    nothingToShow.textColor = [UIColor blackColor];
    nothingToShow.textAlignment = NSTextAlignmentCenter;
    [nothingToShow setNumberOfLines: 0];
    [nothingToShow sizeToFit];

    [nothingToShow setCenter: CGPointMake(_noExperiences.center.x, _noExperiences.center.y)];
    [nothingToShow setFont:[UIFont fontWithName: @"Trebuchet MS" size: 14.0f]];

    [_noExperiences addSubview:nothingToShow];

Answer 1

请尝试快速操作：

let label = UILabel(frame: CGRect(x: 0, y: 0, width: 200, height: 21))
        label.center = view.center
        label.textAlignment = .center
        label.text = "label"
        self.view.addSubview(label)