UILabel检测换行 [英] UILabel detect line breaks

问题描述

我当前正在使用UILabel来显示多行文本.最多将换行符设置为NSLineBreakByWordWrapping，因此标签会自动插入换行符.如何检测这些换行符在哪里?基本上，我想返回一个包含每个\n中断的字符串.

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.

推荐答案

这是我的工作，用于检测UILabel

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"];
}

使用方法

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);

您只需设置 getLinebreaksWithString 所需的参数，您将获得一个包含每个"\ n"中断的字符串.

You just need to set parameters required by getLinebreaksWithString and you will get a string with each "\n" break included.

输出

这篇关于UILabel检测换行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！