iOS. ¡Determine el último ancho de línea de UILabel

Question

chicos! Tengo una etiqueta con varias líneas, lineBreakMode está configurado en UILineBreakModeWordWrap. ¿Cómo puedo determinar el ancho de la última línea? Gracias

Answer 1

Así es como lo hice. Primero coloque las líneas de su etiqueta en NSArray, y luego verifique el ancho de la última línea. En viewDidLoad:

NSArray* lines = [self getSeparatedLinesFromLbl:srcLabel]; 
NSString *lastLine=[lines lastObject]; 
float lastLineWidth=[lastLine sizeWithFont:srcLabel.font constrainedToSize:boundingSize lineBreakMode:NSLineBreakByWordWrapping].width; 

Y getSeparatedLinesFromLbl:

-(NSArray*)getSeparatedLinesFromLbl:(UILabel*)lbl 
{ 
if (lbl.lineBreakMode != NSLineBreakByWordWrapping) 
{ 
    return nil; 
} 

NSMutableArray* lines = [NSMutableArray arrayWithCapacity:10]; 

NSCharacterSet* wordSeparators = [NSCharacterSet whitespaceAndNewlineCharacterSet]; 

NSString* currentLine = lbl.text; 
int textLength = [lbl.text length]; 

NSRange rCurrentLine = NSMakeRange(0, textLength); 
NSRange rWhitespace = NSMakeRange(0,0); 
NSRange rRemainingText = NSMakeRange(0, textLength); 
BOOL done = NO; 
while (!done) 
{ 
    // determine the next whitespace word separator position 
    rWhitespace.location = rWhitespace.location + rWhitespace.length; 
    rWhitespace.length = textLength - rWhitespace.location; 
    rWhitespace = [lbl.text rangeOfCharacterFromSet: wordSeparators options: NSCaseInsensitiveSearch range: rWhitespace]; 
    if (rWhitespace.location == NSNotFound) 
    { 
     rWhitespace.location = textLength; 
     done = YES; 
    } 

    NSRange rTest = NSMakeRange(rRemainingText.location, rWhitespace.location-rRemainingText.location); 

    NSString* textTest = [lbl.text substringWithRange: rTest]; 

    CGSize sizeTest = [textTest sizeWithFont: lbl.font forWidth: 1024.0 lineBreakMode: NSLineBreakByWordWrapping]; 
    if (sizeTest.width > lbl.bounds.size.width) 
    { 
     [lines addObject: [currentLine stringByTrimmingCharactersInSet:wordSeparators]]; 
     rRemainingText.location = rCurrentLine.location + rCurrentLine.length; 
     rRemainingText.length = textLength-rRemainingText.location; 
     continue; 
    } 

    rCurrentLine = rTest; 
    currentLine = textTest; 
} 

[lines addObject: [currentLine stringByTrimmingCharactersInSet:wordSeparators]]; 

return lines; 
} 

Answer 2

Swift 3 (IOS 10,3)

extension UILabel { 
    func getSeparatedLines() -> [Any] { 
     if self.lineBreakMode != NSLineBreakMode.byWordWrapping { 
      self.lineBreakMode = .byWordWrapping 
     } 
     var lines = [Any]() /* capacity: 10 */ 
     let wordSeparators = CharacterSet.whitespacesAndNewlines 
     var currentLine: String? = self.text 
     let textLength: Int = (self.text?.characters.count ?? 0) 
     var rCurrentLine = NSRange(location: 0, length: textLength) 
     var rWhitespace = NSRange(location: 0, length: 0) 
     var rRemainingText = NSRange(location: 0, length: textLength) 
     var done: Bool = false 
     while !done { 
      // determine the next whitespace word separator position 
      rWhitespace.location = rWhitespace.location + rWhitespace.length 
      rWhitespace.length = textLength - rWhitespace.location 
      rWhitespace = (self.text! as NSString).rangeOfCharacter(from: wordSeparators, options: .caseInsensitive, range: rWhitespace) 
      if rWhitespace.location == NSNotFound { 
       rWhitespace.location = textLength 
       done = true 
      } 
      let rTest = NSRange(location: rRemainingText.location, length: rWhitespace.location - rRemainingText.location) 
      let textTest: String = (self.text! as NSString).substring(with: rTest) 
      let fontAttributes: [String: Any]? = [NSFontAttributeName: font] 
      let maxWidth = (textTest as NSString).size(attributes: fontAttributes).width 
      if maxWidth > self.bounds.size.width { 
       lines.append(currentLine?.trimmingCharacters(in: wordSeparators) ?? "") 
       rRemainingText.location = rCurrentLine.location + rCurrentLine.length 
       rRemainingText.length = textLength - rRemainingText.location 
       continue 
      } 
      rCurrentLine = rTest 
      currentLine = textTest 
     } 
     lines.append(currentLine?.trimmingCharacters(in: wordSeparators) ?? "") 
     return lines 
    } 

    var lastLineWidth: CGFloat { 
     let lines: [Any] = self.getSeparatedLines() 
     if !lines.isEmpty { 
      let lastLine: String = (lines.last as? String)! 
      let fontAttributes: [String: Any]? = [NSFontAttributeName: font] 
      return (lastLine as NSString).size(attributes:  fontAttributes).width 
     } 
     return 0 
    } 
} 

Uso

print(yourLabel.lastLineWidth) 

Swift 3 (IOS 10,3)