Xcode - Swift - UILabel 文本高度扩展

Question

我想让 UILabel 的高度根据其文本展开。

这是视图控制器的外观，已选择标签：

这是代码（我尝试了很多不同的类似的东西，但这是我现在拥有的）：

import UIKit

class ViewControllerTEST: UIViewController {

@IBOutlet weak var label: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()


    label.frame = CGRectMake(0, 0, CGRectGetWidth(label.bounds), 0)
    label.numberOfLines = 0
    label.lineBreakMode = .ByWordWrapping
    label.text = "This is a really\nlong string"
    label.setNeedsLayout()
    label.sizeToFit()
    label.frame = CGRectMake(0, 0, CGRectGetWidth(label.bounds), CGRectGetHeight(label.bounds))



}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


/*
// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.
}
*/

}

而且，正如您在此处看到的，它没有按预期工作：

Answer 1

不要使用框架，使用自动布局。为标签添加顶部、前导和尾随约束（我建议在情节提要中这样做）。只要你有lines 等于0（你这样做），高度就会自动调整。如果您想在代码中添加约束，您的 viewDidLoad 将如下所示：

override func viewDidLoad() {
    super.viewDidLoad()
    label.text = "This is a really\nlong string"
    label.setTranslatesAutoresizingMaskIntoConstraints(false)
    view.addSubview(label)
    let views = ["label": label]
    view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-[label]-|", options: nil, metrics: nil, views: views))
    view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-[label]", options: nil, metrics: nil, views: views))
}