UILabel wykrywanie linii podziału

Question

Obecnie używam UILabel do wyświetlania wielu linii tekstu. Najbardziej przełamana linia jest ustawiona na NSLineBreakByWordWrapping, więc etykieta automatycznie wstawia podziały wierszy. Jak mogę wykryć, gdzie znajdują się te podziały wiersza? Zasadniczo chcę zwrócić ciąg z dołączoną przerwą \n.

Answer 1

Oto moja praca wokół wykrywania linii łamie wewnątrz UILabel

- (int)getLengthForString:(NSString *)str fromFrame:(CGRect)frame withFont:(UIFont *)font 
{ 
    int length = 1; 
    int lastSpace = 1; 
    NSString *cutText = [str substringToIndex:length]; 
    CGSize textSize = [cutText sizeWithFont:font constrainedToSize:CGSizeMake(frame.size.width, frame.size.height + 500)]; 
    while (textSize.height <= frame.size.height) 
    { 
     NSRange range = NSMakeRange (length, 1); 
     if ([[str substringWithRange:range] isEqualToString:@" "]) 
     { 
      lastSpace = length; 
     } 
     length++; 
     cutText = [str substringToIndex:length]; 
     textSize = [cutText sizeWithFont:font constrainedToSize:CGSizeMake(frame.size.width, frame.size.height + 500)]; 
    } 
    return lastSpace; 
} 


-(NSString*) getLinebreaksWithString:(NSString*)labelText forWidth:(CGFloat)lblWidth forPoint:(CGPoint)point 
{ 
    //Create Label 
    UILabel *label = [[UILabel alloc] init]; 
    label.text = labelText; 
    label.numberOfLines = 0; 
    label.lineBreakMode = NSLineBreakByWordWrapping; 

    //Set frame according to string 
    CGSize size = [label.text sizeWithFont:label.font 
         constrainedToSize:CGSizeMake(lblWidth, MAXFLOAT) 
          lineBreakMode:UILineBreakModeWordWrap]; 
    [label setFrame:CGRectMake(point.x , point.y , size.width , size.height)]; 

    //Add Label in current view 
    [self.view addSubview:label]; 

    //Count the total number of lines for the Label which has NSLineBreakByWordWrapping line break mode 
    int numLines = (int)(label.frame.size.height/label.font.leading); 

    //Getting and dumping lines from text set on the Label 
    NSMutableArray *allLines = [[NSMutableArray alloc] init]; 

    BOOL shouldLoop = YES; 
    while (shouldLoop) 
    { 
     //Getting length of the string from rect with font 
     int length = [self getLengthForString:labelText fromFrame:CGRectMake(point.x, point.y, size.width, size.height/numLines) withFont:label.font] + 1;   

     [allLines addObject:[labelText substringToIndex:length]]; 

     labelText = [labelText substringFromIndex:length]; 
     if(labelText.length<length) 
      shouldLoop = NO; 
    } 

    [allLines addObject:labelText]; 
    //NSLog(@"\n\n%@\n",allLines); 

    return [allLines componentsJoinedByString:@"\n"]; 
} 

Jak korzystać

NSString *labelText = @"We are what our thoughts have made us; so take care about what you think. Words are secondary. Thoughts live; they travel far."; 

NSString *stringWithLineBreakChar = [self getLinebreaksWithString:labelText forWidth:200 forPoint:CGPointMake(15, 15)]; 
NSLog(@"\n\n%@",stringWithLineBreakChar); 

Trzeba tylko ustawić parametry wymagane przez getLinebreaksWithString i będziesz pobierz ciąg znaków z dołączoną każdą "\ n" przerwą.

wyjście

Answer 2

Oto moje rozwiązanie tego problemu.
Przejmuję wszystkie znaki odstępu w podanym ciągu znaków, ustawiając podciągi (od początku do bieżących białych znaków) i sprawdzam różnicę wysokości. Kiedy wysokość się zmienia, wstawiam nowy znak linii (symuluje podział linii).

func wordWrapFormattedStringFor(string: String) -> String { 
    // Save label state 
    let labelHidden = label.isHidden 
    let labelText = label.text 

    // Set text to current label and size it to fit the content 
    label.isHidden = true 
    label.text = string 
    label.sizeToFit() 
    label.layoutIfNeeded() 

    // Prepare array with indexes of all whitespace characters 
    let whitespaceIndexes: [String.Index] = { 
     let whitespacesSet = CharacterSet.whitespacesAndNewlines 
     var indexes: [String.Index] = [] 

     string.unicodeScalars.enumerated().forEach { i, unicodeScalar in 
      if whitespacesSet.contains(unicodeScalar) { 
       let index = string.index(string.startIndex, offsetBy: i) 
       indexes.append(index) 
      } 
     } 

     // We want also the index after the last character so that when we make substrings later we include also the last word 
     // This index can only be used for substring to this index (not from or including, since it points to \0) 
     let index = string.index(string.startIndex, offsetBy: string.characters.count) 
     indexes.append(index) 

     return indexes 
    }() 

    var reformattedString = "" 

    let boundingSize = CGSize(width: label.bounds.width, height: CGFloat.greatestFiniteMagnitude) 
    let attributes = [NSFontAttributeName: font] 

    var runningHeight: CGFloat? 
    var previousIndex: String.Index? 

    whitespaceIndexes.forEach { index in 
     let string = string.substring(to: index) 
     let stringHeight = string.boundingRect(with: boundingSize, options: .usesLineFragmentOrigin, attributes: attributes, context: nil).height 

     var newString: String = { 
      if let previousIndex = previousIndex { 
       return string.substring(from: previousIndex) 
      } else { 
       return string 
      } 
     }() 

     if runningHeight == nil { 
      runningHeight = stringHeight 
     } 

     if runningHeight! < stringHeight { 
      // Check that we can create a new index with offset of 1 and that newString does not contain only a whitespace (for example if there are multiple consecutive whitespaces) 
      if newString.characters.count > 1 { 
       let splitIndex = newString.index(newString.startIndex, offsetBy: 1) 
       // Insert a new line between the whitespace and rest of the string 
       newString.insert("\n", at: splitIndex) 
      } 
     } 

     reformattedString += newString 

     runningHeight = stringHeight 
     previousIndex = index 
    } 

    // Restore label 
    label.text = labelText 
    label.isHidden = labelHidden 

    return reformattedString 
} 

Image - Comparison of output string with label text.

Rozwiązanie to działało bardzo dobrze w moim przypadku, mam nadzieję, że to pomaga.