在 Swift 中根据 String 计算 UILabel 的大小 [英] Figure out size of UILabel based on String in Swift

问题描述

我正在尝试根据不同的字符串长度计算 UILabel 的高度.

I am trying to calculate the height of a UILabel based on different String lengths.

func calculateContentHeight() -> CGFloat{
    var maxLabelSize: CGSize = CGSizeMake(frame.size.width - 48, CGFloat(9999))
    var contentNSString = contentText as NSString
    var expectedLabelSize = contentNSString.boundingRectWithSize(maxLabelSize, options: NSStringDrawingOptions.UsesLineFragmentOrigin, attributes: [NSFontAttributeName: UIFont.systemFontOfSize(16.0)], context: nil)
    print("(expectedLabelSize)")
    return expectedLabelSize.size.height

}

上面是我用来确定高度的当前函数，但它不起作用.我将非常感谢我能得到的任何帮助.我更喜欢 Swift 而不是 Objective C 中的答案.

Above is the current function I use to determine the height but it is not working. I would greatly appreciate any help I can get. I would perfer the answer in Swift and not Objective C.

推荐答案

在String上使用扩展

extension String {
    func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
    
        return ceil(boundingBox.height)
    }

    func width(withConstrainedHeight height: CGFloat, font: UIFont) -> CGFloat {
        let constraintRect = CGSize(width: .greatestFiniteMagnitude, height: height)
        let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)

        return ceil(boundingBox.width)
    }
}

还有 NSAttributedString (有时非常有用)

and also on NSAttributedString (which is very useful at times)

extension NSAttributedString {
    func height(withConstrainedWidth width: CGFloat) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        let boundingBox = boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil)
    
        return ceil(boundingBox.height)
    }

    func width(withConstrainedHeight height: CGFloat) -> CGFloat {
        let constraintRect = CGSize(width: .greatestFiniteMagnitude, height: height)
        let boundingBox = boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil)
    
        return ceil(boundingBox.width)
    }
}

斯威夫特 4 &5

只需在 extension String 方法中更改 attributes 的值

来自

[NSFontAttributeName: font]

到

[.font : font]

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