UILabel detect line breaks - nsstring

Question

I am currently using a UILabel to display multiple lines of text. The line break most is set to NSLineBreakByWordWrapping so the the label automatically inserts line breaks. How can I detect where those line breaks are? Basically, I want to return a string with each \n break included.

Answer 1

Here is my work around for detecting line breaks inside 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"];
}
How to use
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);
You just need to set parameters required by getLinebreaksWithString and you will get a string with each "\n" break included.
OutPut

Answer 2

Here is my solution to this problem.
I iterate through all whitespace characters in the provided string, set substrings (from beginning to current whitespace) to my label and check the difference in the height. When the height changes I insert a new line character (simulates a line break).
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.
This solution worked really well in my case, hope it helps.