问题:

I have a UILabel that displays some chars. Like "x", "y" or "rpm". How can I calculate the width of the text in the label (it does not ues the whole available space)? This is for automatic layouting, where another view will have a bigger frame rectangle if that UILabel has a smaller text inside. Are there methods to calculate that width of the text when a UIFont and font size is specified? There's also no line-break and just one single line.

回答1:

You can do exactly that via the various sizeWithFont: methods in NSString UIKit Additions. In your case the simplest variant should suffice (since you don't have multi-line labels):

NSString *someString = @"Hello World"; UIFont *yourFont = // [UIFont ...] CGSize stringBoundingBox = [someString sizeWithFont:yourFont];

There are several variations of this method, eg. some consider line break modes or maximum sizes.

回答2:

sizeWithFont: is now deprecated, use sizeWithAttributes: instead:

UIFont *font = [UIFont fontWithName:@"Helvetica" size:30]; NSDictionary *userAttributes = @{NSFontAttributeName: font,                                  NSForegroundColorAttributeName: [UIColor blackColor]}; NSString *text = @"hello"; ... const CGSize textSize = [text sizeWithAttributes: userAttributes];

回答3:

Since sizeWithFont is deprecated, I'm just going to update my original answer to using Swift 4 and .size

//: Playground - noun: a place where people can play  import UIKit  if let font = UIFont(name: "Helvetica", size: 24) {    let fontAttributes = [NSAttributedStringKey.font: font]    let myText = "Your Text Here"    let size = (myText as NSString).size(withAttributes: fontAttributes) }

The size should be the onscreen size of "Your Text Here" in points.

回答4:

Based on Glenn Howes' excellent answer, I created an extension to calculate the width of a string. If you're doing something like setting the width of a UISegmentedControl, this can set the width based on the segment's title string.

extension String {      func widthOfString(usingFont font: UIFont) -> CGFloat {         let fontAttributes = [NSFontAttributeName: font]         let size = self.size(attributes: fontAttributes)         return size.width     }      func heightOfString(usingFont font: UIFont) -> CGFloat {         let fontAttributes = [NSFontAttributeName: font]         let size = self.size(attributes: fontAttributes)         return size.height     } }

usage:

Swift 4

func widthOfString(usingFont font: UIFont) -> CGFloat {     let fontAttributes = [NSAttributedStringKey.font: font]     let size = self.size(withAttributes: fontAttributes)     return size.width }  func heightOfString(usingFont font: UIFont) -> CGFloat {     let fontAttributes = [NSAttributedStringKey.font: font]     let size = self.size(withAttributes: fontAttributes)     return size.height }  func sizeOfString(usingFont font: UIFont) -> CGSize {   let fontAttributes = [NSAttributedStringKey.font: font]   return self.size(withAttributes: fontAttributes) }

回答5:

This simple extension in Swift works well.

extension String {     func size(OfFont font: UIFont) -> CGSize {         return (self as NSString).size(attributes: [NSFontAttributeName: font])     } }

Usage:

let string = "hello world!" let font = UIFont.systemFont(ofSize: 12) let width = string.size(OfFont: font).width // size: {w: 98.912 h: 14.32}

回答6:

This is for swift 2.3 Version. You can get the width of string.

var sizeOfString = CGSize() if let font = UIFont(name: "Helvetica", size: 14.0)     {         let finalDate = "Your Text Here"         let fontAttributes = [NSFontAttributeName: font] // it says name, but a UIFont works         sizeOfString = (finalDate as NSString).sizeWithAttributes(fontAttributes)     }

回答7:

For Swift 4.2

func SizeOf_String( font: UIFont) -> CGSize {     let fontAttribute = [NSAttributedStringKey.font: font]     let size = self.size(withAttributes: fontAttribute)  // for Single Line     return size; }

Not tested yet...

回答8:

For Swift 3.0+

extension String {     func SizeOf_String( font: UIFont) -> CGSize {         let fontAttribute = [NSFontAttributeName: font]         let size = self.size(attributes: fontAttribute)  // for Single Line        return size;    } }

Use it like...

        let Str = "ABCDEF"         let Font =  UIFont.systemFontOfSize(19.0)         let SizeOfString = Str.SizeOfString(font: Font!)

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