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;

创建一个接受UILabel实例的函数。并返回CGSize

CGSize constraint = CGSizeMake(label.frame.size.width , 2000.0);
// Adjust according to requirement

CGSize size;
if([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0){

    NSRange range = NSMakeRange(0, [label.attributedText length]);

    NSDictionary *attributes = [label.attributedText attributesAtIndex:0 effectiveRange:&range];
    CGSize boundingBox = [label.text boundingRectWithSize:constraint options: NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size;

    size = CGSizeMake(ceil(boundingBox.width), ceil(boundingBox.height));
}
else{
    size = [label.text sizeWithFont:label.font constrainedToSize:constraint lineBreakMode:label.lineBreakMode];
}

return size;

正如@Ayush的回答:

正如你在苹果开发者网站上看到的sizeWithFont，它已被弃用，所以我们需要使用sizeWithAttributes。

好吧，假设在2019+你可能会使用Swift和String而不是Objective-c和NSString，下面是使用预定义字体获取字符串大小的正确方法:

let stringSize = NSString(string: label.text!).size(withAttributes: [.font : UIFont(name: "OpenSans-Regular", size: 15)!])

CGSize maximumLabelSize = CGSizeMake(label.frame.size.width, FLT_MAX);
CGSize expectedLabelSize = [label sizeThatFits:maximumLabelSize];
float heightUse = expectedLabelSize.height;

最好使用自动尺寸(Swift):

  tableView.estimatedRowHeight = 68.0
  tableView.rowHeight = UITableViewAutomaticDimension

注: 1. UITableViewCell原型应该正确设计(对于实例不要忘记设置UILabel。numberolines = 0 etc) 2. 删除hightforrowatindexpath方法

视频: https://youtu.be/Sz3XfCsSb6k

正如你在苹果开发者网站上看到的sizeWithFont，它已被弃用，所以我们需要使用sizeWithAttributes。

#define SYSTEM_VERSION_LESS_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)

NSString *text = @"Hello iOS 7.0";
if (SYSTEM_VERSION_LESS_THAN(@"7.0")) {
    // code here for iOS 5.0,6.0 and so on
    CGSize fontSize = [text sizeWithFont:[UIFont fontWithName:@"Helvetica" 
                                                         size:12]];
} else {
    // code here for iOS 7.0
   CGSize fontSize = [text sizeWithAttributes: 
                            @{NSFontAttributeName: 
                              [UIFont fontWithName:@"Helvetica" size:12]}];
}