UILabel *itemTitle = [[UILabel alloc] initWithFrame:CGRectMake(10.0f, 10,100, 200.0f)];
itemTitle.text = @"aseruy56uiytitfesh";
itemTitle.adjustsFontSizeToFitWidth = NO;
itemTitle.autoresizingMask = UIViewAutoresizingFlexibleWidth;
itemTitle.font = [UIFont boldSystemFontOfSize:18.0];
itemTitle.textColor = [UIColor blackColor];
itemTitle.shadowColor = [UIColor whiteColor];
itemTitle.shadowOffset = CGSizeMake(0, 1);
itemTitle.backgroundColor = [UIColor blueColor];
itemTitle.lineBreakMode = UILineBreakModeWordWrap;
itemTitle.numberOfLines = 0;
[itemTitle sizeToFit];
[self.view addSubview:itemTitle];

使用这里所有的属性都使用在标签上，并通过增加itemTitle中的文本来测试它。文本

itemTitle.text = @"diofgorigjveghnhkvjteinughntivugenvitugnvkejrfgnvkhv";

它会根据你的需要给出完美的答案

此方法适用于iOS 6和7

- (float)heightForLabelSize:(CGSize)maximumLabelSize  Font:(UIFont *)font String:(NSString*)string {

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7) {
    NSDictionary *stringAttributes = [NSDictionary dictionaryWithObject:font forKey: NSFontAttributeName];

    CGSize adjustedLabelSize = [string maximumLabelSize
                                                                  options:NSStringDrawingTruncatesLastVisibleLine|NSStringDrawingUsesLineFragmentOrigin
                                                               attributes:stringAttributes context:nil].size;
    return adjustedLabelSize.height;
}
else {
    CGSize adjustedLabelSize = [string sizeWithFont:font constrainedToSize:maximumLabelSize lineBreakMode:NSLineBreakByWordWrapping];

    return adjustedLabelSize.height;
}

}

你可以通过以下方式实现TableViewController的(UITableViewCell *)tableView:cellForRowAtIndexPath方法(例如):

#define CELL_LABEL_TAG 1

- (UITableViewCell *)tableView:(UITableView *)tableView  cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    NSString *text = @"my long text";

    static NSString *MyIdentifier = @"MyIdentifier";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero  reuseIdentifier:identifier] autorelease];
    }

    CGFloat width = [UIScreen mainScreen].bounds.size.width - 50;
    CGFloat height = [self textHeight:text] + 10;
    CGRect frame = CGRectMake(10.0f, 10.0f, width, height);

    UILabel *cellLabel = [[UILabel alloc] initWithFrame:frame];
    cellLabel.tag = CELL_LABEL_TAG;
    cellLabel.textColor = [UIColor blackColor];
    cellLabel.backgroundColor = [UIColor clearColor];
    cellLabel.textAlignment = UITextAlignmentLeft;
    cellLabel.font = [UIFont systemFontOfSize:12.0f];
    [cell.contentView addSubview:cellLabel];
    [cellLabel release];

    return cell;
}

UILabel *label = (UILabel *)[cell viewWithTag:CELL_LABEL_TAG];
label.text = text;
label.numberOfLines = 0;
[label sizeToFit];
return cell;

也可以使用NSString的sizeWithFont:constrainedToSize:lineBreakMode:方法来计算文本的高度。

基于Swift 4及以上答案的UILabel扩展

extension UILabel {

    func retrieveTextHeight () -> CGFloat {
        let attributedText = NSAttributedString(string: self.text!, attributes: [NSFontAttributeName:self.font])

        let rect = attributedText.boundingRect(with: CGSize(width: self.frame.size.width, height: CGFloat.greatestFiniteMagnitude), options: .usesLineFragmentOrigin, context: nil)

        return ceil(rect.size.height)
    }

}

可以这样使用:

self.labelHeightConstraint.constant = self.label.retrieveTextHeight()

对于那些迁移到iOS 8的人，这里有一个Swift的类扩展:

extension UILabel {

    func autoresize() {
        if let textNSString: NSString = self.text {
            let rect = textNSString.boundingRectWithSize(CGSizeMake(self.frame.size.width, CGFloat.max),
                options: NSStringDrawingOptions.UsesLineFragmentOrigin,
                attributes: [NSFontAttributeName: self.font],
                context: nil)
            self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, self.frame.size.width, rect.height)
        }
    }

}

你可以使用下面的代码得到高度

你必须通过

文本2。字体3。标签宽度 func hightforlabel (text: String, font: UIFont, width: CGFloat) -> CGFloat { let label:UILabel = UILabel(frame: CGRect(x: 0, y: 0, width: width, height: CGFloat.greatestFiniteMagnitude)) 标签。numberolines = 0 标签。lineBreakMode = nslinebreakmode . bywordwrapped 标签。Font = Font 标签。Text = Text label.sizeToFit () 返回label.frame.height ｝