斯威夫特4:

// attribute with color red and Bold
var attrs1 = [NSAttributedStringKey.font: UIFont.boldSystemFont(ofSize: 20), NSAttributedStringKey.foregroundColor: UIColor.red]

// attribute with color black and Non Bold
var attrs2 = [NSAttributedStringKey.font: UIFont(name: "Roboto-Regular", size: 20), NSAttributedStringKey.foregroundColor: UIColor.black]  

var color1 = NSAttributedString(string: "RED", attributes: attrs1)

var color2 = NSAttributedString(string: " BLACK", attributes: attrs2)

var string = NSMutableAttributedString()

string.append(color1)

string.append(color2)

// print the text with **RED** BLACK
print("Final String : \(string)")

AttributeString构造函数,把马克字符串,这样做可能意味着你的属性字符串没有其他属性,因此,如果您使用的是xib,你可以没有大胆的文本,将所有你想要的其他属性,然后通过属性在代码中列举范围你记下的字符串,并将它们应用于带属性字符串从你xib文件,然后重新申请你认为AttributeString特定领域。

在这种情况下，你可以尝试，

UILabel *displayLabel = [[UILabel alloc] initWithFrame:/*label frame*/];
displayLabel.font = [UIFont boldSystemFontOfSize:/*bold font size*/];

NSMutableAttributedString *notifyingStr = [[NSMutableAttributedString alloc] initWithString:@"Updated: 2012/10/14 21:59 PM"];
[notifyingStr beginEditing];
[notifyingStr addAttribute:NSFontAttributeName
                     value:[UIFont systemFontOfSize:/*normal font size*/]
                     range:NSMakeRange(8,10)/*range of normal string, e.g. 2012/10/14*/];
[notifyingStr endEditing];

displayLabel.attributedText = notifyingStr; // or [displayLabel setAttributedText: notifyingStr];

NSString *needToChangeStr=@"BOOK";
NSString *display_string=[NSString stringWithFormat:@"This is %@",book];

NSMutableAttributedString *attri_str=[[NSMutableAttributedString alloc]initWithString:display_string];

int begin=[display_string length]-[needToChangeStr length];
int end=[needToChangeStr length];


[attri_str addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"HelveticaNeue-Bold" size:30] range:NSMakeRange(begin, end)];

如果您希望更容易地使用带属性字符串，请尝试使用带属性字符串创建者，它将为您生成代码。https://itunes.apple.com/us/app/attributed-string-creator/id730928349

我采用了疯狂酸奶对斯威夫特扩展的回答。

extension UILabel {

    func boldRange(_ range: Range<String.Index>) {
        if let text = self.attributedText {
            let attr = NSMutableAttributedString(attributedString: text)
            let start = text.string.characters.distance(from: text.string.startIndex, to: range.lowerBound)
            let length = text.string.characters.distance(from: range.lowerBound, to: range.upperBound)
            attr.addAttributes([NSFontAttributeName: UIFont.boldSystemFont(ofSize: self.font.pointSize)], range: NSMakeRange(start, length))
            self.attributedText = attr
        }
    }

    func boldSubstring(_ substr: String) {
        if let text = self.attributedText {
            var range = text.string.range(of: substr)
            let attr = NSMutableAttributedString(attributedString: text)
            while range != nil {
                let start = text.string.characters.distance(from: text.string.startIndex, to: range!.lowerBound)
                let length = text.string.characters.distance(from: range!.lowerBound, to: range!.upperBound)
                var nsRange = NSMakeRange(start, length)
                let font = attr.attribute(NSFontAttributeName, at: start, effectiveRange: &nsRange) as! UIFont
                if !font.fontDescriptor.symbolicTraits.contains(.traitBold) {
                    break
                }
                range = text.string.range(of: substr, options: NSString.CompareOptions.literal, range: range!.upperBound..<text.string.endIndex, locale: nil)
            }
            if let r = range {
                boldRange(r)
            }
        }
    }
}

可能在Range和NSRange之间没有很好的转换，但我没有发现更好的东西。