ios - 根据 Swift 中的文本大小调整 labelSize

Question

我已经以编程方式向 UIView 添加了一个标签。但是我似乎无法根据标签内的文本自动调整大小。我尝试过使用此扩展，但不确定如何正确使用它

extension UILabel {
    func resizeHeightToFit(heightConstraint: NSLayoutConstraint) {
        let attributes = [NSFontAttributeName : font]
        numberOfLines = 0
        lineBreakMode = NSLineBreakMode.ByWordWrapping
        let rect = text!.boundingRectWithSize(CGSizeMake(frame.size.width, CGFloat.max), options: NSStringDrawingOptions.UsesLineFragmentOrigin, attributes: attributes, context: nil)
        heightConstraint.constant = rect.height
        setNeedsLayout()
    }
}

然后我尝试了这个:

titleLabel?.resizeHeightToFit(NSLayoutConstraint(item: self, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1.0, constant: titleLabel!.frame.height))

但它返回错误。

Answer 1

你可以试试sizeToFit():

let label = UILabel()
label.text = "Text"
label.sizeToFit()
print(label.frame) // "(0.0, 0.0, 32.5, 20.5)"
label.text = "Text that is pretty long this time"
label.sizeToFit()
print(label.frame) // "(0.0, 0.0, 241.5, 20.5)"