iOS UIlabel内容以后添加全文/展开

传入初始化frame以后的lab ，返回的是每行的string。

经过计算最后一行string的rect 获得全文/扩展btn的x,y值 

-(NSArray *)getSeparatedLinesFromLabel:(UILabel *)label
{
    NSString *text = [label text];
    UIFont   *font = [label font];
    CGRect    rect = [label frame];
    
    CTFontRef myFont = CTFontCreateWithName((__bridge CFStringRef)([font fontName]), [font pointSize], NULL);
    NSMutableAttributedString *attStr = [[NSMutableAttributedString alloc] initWithString:text];
    [attStr addAttribute:(NSString *)kCTFontAttributeName value:(__bridge id)myFont range:NSMakeRange(0, attStr.length)];
    
    CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef)attStr);
    
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, NULL, CGRectMake(0,0,rect.size.width,100000));
    
    CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, 0), path, NULL);
    
    NSArray *lines = (__bridge NSArray *)CTFrameGetLines(frame);
    NSMutableArray *linesArray = [[NSMutableArray alloc]init];
    
    for (id line in lines)
    {
        CTLineRef lineRef = (__bridge CTLineRef )line;
        CFRange lineRange = CTLineGetStringRange(lineRef);
        NSRange range = NSMakeRange(lineRange.location, lineRange.length);
        
        NSString *lineString = [text substringWithRange:range];
        [linesArray addObject:lineString];
    }
    return (NSArray *)linesArray;
}

 

以下所示

btn紧随最后一行文字的后面

NSArray * arr = [self getSeparatedLinesFromLabel:_lab];
    
    CGRect rect = [[arr lastObject] boundingRectWithSize:CGSizeMake(SREENWIDTH, MAXFLOAT) options:NSStringDrawingUsesFontLeading | NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:15]} context:nil];
    
    UIButton * btn = [UIButton buttonWithType:UIButtonTypeCustom];
    btn.frame = CGRectMake(rect.size.width+10, (arr.count-1)*(rect.size.height), 50, rect.size.height);
    [btn setTitle:@"全文" forState:UIControlStateNormal];
    [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    [btn addTarget:self action:@selector(method) forControlEvents:UIControlEventTouchUpInside];
    
    
    _lab.frame = CGRectMake(0, 60, SREENWIDTH, CGRectGetMaxY(btn.frame));
    _lab.userInteractionEnabled = YES;
    
    [self.view addSubview:_lab];
    [_lab addSubview:btn];

 

截取的文字长度，替换的文字自行处理

点击全文把以前的text从新赋值给lab ,从新计算frame便可