这是基于bbrame的category的category。它的工作原理类似，但允许您在累积结果中多次加粗相同的UILabel。

UILabel h +及。

@interface UILabel (Boldify)
- (void) boldSubstring: (NSString*) substring;
- (void) boldRange: (NSRange) range;
@end

UILabel + Boldify.m

@implementation UILabel (Boldify)
- (void)boldRange:(NSRange)range {
    if (![self respondsToSelector:@selector(setAttributedText:)]) {
        return;
    }
    NSMutableAttributedString *attributedText;
    if (!self.attributedText) {
        attributedText = [[NSMutableAttributedString alloc] initWithString:self.text];
    } else {
        attributedText = [[NSMutableAttributedString alloc] initWithAttributedString:self.attributedText];
    }
    [attributedText setAttributes:@{NSFontAttributeName:[UIFont boldSystemFontOfSize:self.font.pointSize]} range:range];
    self.attributedText = attributedText;
}

- (void)boldSubstring:(NSString*)substring {
    NSRange range = [self.text rangeOfString:substring];
    [self boldRange:range];
}
@end

有了这个修正，你可以多次使用它，例如:

myLabel.text = @"Updated: 2012/10/14 21:59 PM";
[myLabel boldSubstring: @"Updated:"];
[myLabel boldSubstring: @"21:59 PM"];

将会得到:“更新日期:2012/10/14 21:59 PM”。

在UILabel中使文本加粗并加下划线。只需在代码中添加以下行。

NSRange range1 = [lblTermsAndCondition.text rangeOfString:NSLocalizedString(@"bold_terms", @"")];
NSRange range2 = [lblTermsAndCondition.text rangeOfString:NSLocalizedString(@"bold_policy", @"")];
NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:lblTermsAndCondition.text];
[attributedText setAttributes:@{NSFontAttributeName:[UIFont fontWithName:fontBold size:12.0]}
                        range:range1];
[attributedText setAttributes:@{NSFontAttributeName:[UIFont fontWithName:fontBold size:12.0]}
                        range:range2];


[attributedText addAttribute:(NSString*)kCTUnderlineStyleAttributeName
                  value:[NSNumber numberWithInt:kCTUnderlineStyleSingle]
                  range:range1];

[attributedText addAttribute:(NSString*)kCTUnderlineStyleAttributeName
                       value:[NSNumber numberWithInt:kCTUnderlineStyleSingle]
                       range:range2];



lblTermsAndCondition.attributedText = attributedText;

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)];

检查TTTAttributedLabel。它是UILabel的一个替换，它允许你在一个标签中混合字体和颜色，通过设置NSAttributedString作为标签的文本。

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。

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)")