iOS : How to align labels like whatsapp chat message label and time label?

Question

在whatsapp中，如果消息很短，文本和时间在同一行。如果消息很长，时间在右下角 - 上面的文字。

我如何在 Ios 中使用 Storyboard 实现此目的

Answer 1

尝试使用类似这样的方法来定义最后一行的宽度(也许您需要针对您的情况稍微调整文本容器):

public func lastLineMaxX(message: NSAttributedString, labelWidth: CGFloat) -> CGFloat {
    // Create instances of NSLayoutManager, NSTextContainer and NSTextStorage
    let labelSize = CGSize(width: bubbleWidth, height: .infinity)
    let layoutManager = NSLayoutManager()
    let textContainer = NSTextContainer(size: labelSize)
    let textStorage = NSTextStorage(attributedString: message)

    // Configure layoutManager and textStorage
    layoutManager.addTextContainer(textContainer)
    textStorage.addLayoutManager(layoutManager)

    // Configure textContainer
    textContainer.lineFragmentPadding = 0.0
    textContainer.lineBreakMode = .byWordWrapping
    textContainer.maximumNumberOfLines = 0

    let lastGlyphIndex = layoutManager.glyphIndexForCharacter(at: message.length - 1)
    let lastLineFragmentRect = layoutManager.lineFragmentUsedRect(forGlyphAt: lastGlyphIndex,
                                                                  effectiveRange: nil)

    return lastLineFragmentRect.maxX
}

然后你可以决定最后一行是否有足够的地方放置你的日期标签

使用示例:

// you definitely have to set at least the font to calculate the result
// maybe for your case you will also have to set other attributes
let attributedText = NSAttributedString(string: self.label.text, 
                                        attributes: [.font: self.label.font])
let lastLineMaxX = lastLineMaxX(message: attributedText, 
                                labelWidth: self.label.bounds.width)