Objective C - UILabel multiline vertical gap height

问题

I have a multiline UILabel that can take a maximum of 3 lines. i.e message.numberOfLines = 3;

Everything works fine, but how can I set the vertical gap between the lines? e.g between line 1 and line 2 etc?

Please enlight,
Tee

回答1:

I haven't been able to find a way to adjust the spacing between lines. The font property of UILabel has a number of read-only properties, so that won't help.

I've resorted to draw my own text if I want to change the line spacing. I use NSString's -drawAtPoint and -drawInRect and use one or more of the -sizeWithFont methods to figure out how long the text will be in order to split the text and draw the right number of words or characters per line.

回答2:

Unfortunately, the only good way to do this that I'm aware of is to draw the text yourself. On 3.2 or later, you can use CoreText to draw the text directly - I'm not sure if CT is available on iPhones >= 4.0. CoreText is a functional C API for flexible text drawing.

回答3:

Programmatically:

SWift 4

Using label extension

extension UILabel {

    // Pass value for any one of both parameters and see result
    func setLineSpacing(lineSpacing: CGFloat = 0.0, lineHeightMultiple: CGFloat = 0.0) {

        guard let labelText = self.text else { return }

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineSpacing = lineSpacing
        paragraphStyle.lineHeightMultiple = lineHeightMultiple

        let attributedString:NSMutableAttributedString
        if let labelattributedText = self.attributedText {
            attributedString = NSMutableAttributedString(attributedString: labelattributedText)
        } else {
            attributedString = NSMutableAttributedString(string: labelText)
        }

        // Line spacing attribute
        attributedString.addAttribute(NSAttributedStringKey.paragraphStyle, value:paragraphStyle, range:NSMakeRange(0, attributedString.length))

        self.attributedText = attributedString
    }
}

Now call extension function

let label = UILabel()
let stringValue = "How to\ncontrol\nthe\nline spacing\nin UILabel"

// Pass value for any one argument - lineSpacing or lineHeightMultiple
label.setLineSpacing(lineSpacing: 2.0) .  // try values 1.0 to 5.0

// or try lineHeightMultiple
//label.setLineSpacing(lineHeightMultiple = 2.0) // try values 0.5 to 2.0

Or using label instance (Just copy & execute this code to see result)

let label = UILabel()
let stringValue = "How to\ncontrol\nthe\nline spacing\nin UILabel"
let attrString = NSMutableAttributedString(string: stringValue)
var style = NSMutableParagraphStyle()
style.lineSpacing = 24 // change line spacing between paragraph like 36 or 48
style.minimumLineHeight = 20 // change line spacing between each line like 30 or 40

// Line spacing attribute
attrString.addAttribute(NSAttributedStringKey.paragraphStyle, value: style, range: NSRange(location: 0, length: stringValue.characters.count))

// Character spacing attribute
attrString.addAttribute(NSAttributedStringKey.kern, value: 2, range: NSMakeRange(0, attrString.length))

label.attributedText = attrString

From Interface Builder:

来源：https://stackoverflow.com/questions/1737092/objective-c-uilabel-multiline-vertical-gap-height

标签

objective-c

iphone

uilabel

line-spacing