当自动布局被启用时，调整大小不工作:)

我的代码:

UILabel *label      = [[UILabel alloc] init];
label.numberOfLines = 0;
label.lineBreakMode = NSLineBreakByWordWrapping;
label.text          = text;
label.textAlignment = NSTextAlignmentCenter;
label.font          = [UIFont fontWithName:_bodyTextFontFamily size:_bodyFontSize];

CGSize size = [label sizeThatFits:CGSizeMake(width, MAXFLOAT)];


float height        = size.height;
label.frame         = CGRectMake(x, y, width, height);

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;
}

}

我计算UILabel动态高度的方法。

    let width = ... //< width of this label 
    let text = ... //< display content

    label.numberOfLines = 0
    label.lineBreakMode = .byWordWrapping
    label.preferredMaxLayoutWidth = width

    // Font of this label.
    //label.font = UIFont.systemFont(ofSize: 17.0)
    // Compute intrinsicContentSize based on font, and preferredMaxLayoutWidth
    label.invalidateIntrinsicContentSize() 
    // Destination height
    let height = label.intrinsicContentSize.height

包装功能:

func computeHeight(text: String, width: CGFloat) -> CGFloat {
    // A dummy label in order to compute dynamic height.
    let label = UILabel()

    label.numberOfLines = 0
    label.lineBreakMode = .byWordWrapping
    label.font = UIFont.systemFont(ofSize: 17.0)

    label.preferredMaxLayoutWidth = width
    label.text = text
    label.invalidateIntrinsicContentSize()

    let height = label.intrinsicContentSize.height
    return height
}

由于sizeWithFont已弃用，我使用这个代替。

这个得到标签特定属性。

-(CGFloat)heightForLabel:(UILabel *)label withText:(NSString *)text{

    NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:text attributes:@{NSFontAttributeName:label.font}];
    CGRect rect = [attributedText boundingRectWithSize:(CGSize){label.frame.size.width, CGFLOAT_MAX}
                                           options:NSStringDrawingUsesLineFragmentOrigin
                                           context:nil];

    return ceil(rect.size.height);
}

最后，它成功了。谢谢大家。

我没有让它工作，因为我试图在heightForRowAtIndexPath方法中调整标签的大小:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath

和(是的，我很傻)，我在cellForRowAtIndexPath方法中调整标签的默认大小-我忽略了我之前写的代码:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath