替代解决方案,

CGSize expectedLabelSize;
if ([subTitle respondsToSelector:@selector(sizeWithAttributes:)])
{
    expectedLabelSize = [subTitle sizeWithAttributes:@{NSFontAttributeName:subTitleLabel.font}];
}else{
    expectedLabelSize = [subTitle sizeWithFont:subTitleLabel.font constrainedToSize:subTitleLabel.frame.size lineBreakMode:NSLineBreakByWordWrapping];
}

你仍然可以使用sizeWithFont。但是，在iOS >= 7.0中，如果字符串包含开头和结尾空格或结束行\n，则会导致崩溃。

在使用文本之前修剪文本

label.text = [label.text stringByTrimmingCharactersInSet:
             [NSCharacterSet whitespaceAndNewlineCharacterSet]];

这也适用于sizeWithAttributes和[label sizeToFit]。

此外，当你有nsstringdrawingtextstorage消息发送到deallocated实例在ios7.0设备它处理这个。

使用动态高度的多行标签可能需要额外的信息来正确设置大小。你可以使用sizeWithAttributes with UIFont和NSParagraphStyle来指定字体和换行模式。

你可以像这样定义段落样式并使用NSDictionary:

// set paragraph style
NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
[style setLineBreakMode:NSLineBreakByWordWrapping];
// make dictionary of attributes with paragraph style
NSDictionary *sizeAttributes        = @{NSFontAttributeName:myLabel.font, NSParagraphStyleAttributeName: style};
// get the CGSize
CGSize adjustedSize = CGSizeMake(label.frame.size.width, CGFLOAT_MAX);

// alternatively you can also get a CGRect to determine height
CGRect rect = [myLabel.text boundingRectWithSize:adjustedSize
                                                         options:NSStringDrawingUsesLineFragmentOrigin
                                                      attributes:sizeAttributes
                                                         context:nil];

你可以使用CGSize ' adjuststedsize '或CGRect作为矩形。size.height属性如果你在寻找高度。

更多关于NSParagraphStyle的信息请访问:https://developer.apple.com/library/mac/documentation/cocoa/reference/applicationkit/classes/NSParagraphStyle_Class/Reference/Reference.html

改用sizeWithAttributes:，它现在接受一个NSDictionary。传入key UITextAttributeFont和你的字体对象，如下所示:

CGRect rawRect = {};
rawRect.size = [string sizeWithAttributes: @{
    NSFontAttributeName: [UIFont systemFontOfSize:17.0f],
}];

// Values are fractional -- you should take the ceil to get equivalent values
CGSize adjustedSize = CGRectIntegral(rawRect).size;

试试这个语法:

NSAttributedString *attributedText =
    [[NSAttributedString alloc] initWithString:text 
                                    attributes:@{NSFontAttributeName: font}];

基于@bitsand，这是一个新方法，我刚刚添加到我的NSString+Extras类别:

- (CGRect) boundingRectWithFont:(UIFont *) font constrainedToSize:(CGSize) constraintSize lineBreakMode:(NSLineBreakMode) lineBreakMode;
{
    // set paragraph style
    NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
    [style setLineBreakMode:lineBreakMode];

    // make dictionary of attributes with paragraph style
    NSDictionary *sizeAttributes = @{NSFontAttributeName:font, NSParagraphStyleAttributeName: style};

    CGRect frame = [self boundingRectWithSize:constraintSize options:NSStringDrawingUsesLineFragmentOrigin attributes:sizeAttributes context:nil];

    /*
    // OLD
    CGSize stringSize = [self sizeWithFont:font
                              constrainedToSize:constraintSize
                                  lineBreakMode:lineBreakMode];
    // OLD
    */

    return frame;
}

我只是使用结果帧的大小。