How can I prevent orphans in a label in swift?

问题

I have a label that can have one or two lines. If it has two lines, I want the second line to have at least two (or maybe three) words, never just one. Any ideas about how I can accomplish that using swift?

Thanks in advance!

Daniel

Edit: I edited out my silly first thoughts that didn't really help.

回答1:

Ok, after looking around a lot I came up with what I think is the best solution.

I wrote this function:

func numberOfLinesInLabelForText(text: String) -> Int {

    let attributes = [NSFontAttributeName : UIFont.preferredFontForTextStyle(UIFontTextStyleHeadline)]
    let screenSize: CGRect = UIScreen.mainScreen().bounds
    let labelSize = text!.boundingRectWithSize(CGSizeMake((screenSize.width - 30), CGFloat.max), options: NSStringDrawingOptions.UsesLineFragmentOrigin, attributes: attributes, context: nil)

    let lines = floor(CGFloat(labelSize.height) / bookTitleLabel.font.lineHeight)
    return Int(lines)
}

You put in the string that will be displayed in the label and it gives you how many lines the label will have. I'm using dynamic type and the Headline style for this particular label, hence the preferredFontForTextStyle(UIFontTextStyleHeadline) part, but you can change that to the font and size your label uses. Then I use (screenSize.width - 30) for my label's width because it's width is not fixed, so I'm using the screen size minus leading and trailing. This is probably not the most elegant solution, I'm open to better suggestions. The rest is pretty straightforward.

After I have the number of lines I can do this:

func splittedString(text: String) -> String {

    if numberOfLinesInLabel(text) == 2 {
        var chars = Array(text.characters)
        var i = chars.count / 2
        var x = chars.count / 2
        while chars[i] != " " && chars[x] != " " {
            i--
            x++
        }
        if chars[i] == " " {
            chars.insert("\n", atIndex: i+1)
        } else {
            chars.insert("\n", atIndex: x+1)
        }
        return String(chars)
    }
}

Instead of just avoiding orphans I decided to split the string in two at the breaking point nearest to its half, so that's what this last function does, but it wouldn't be hard to tweak it to suit your needs.

And there you have it!

来源：https://stackoverflow.com/questions/33228302/how-can-i-prevent-orphans-in-a-label-in-swift

标签

ios

string

swift

uilabel