字符串分类

-(NSMutableAttributedString *)keyWords:(NSString *)keyWords withKeyWordsColor:(UIColor *)color
{
    
    NSMutableAttributedString *mutableAttributedStr = [[NSMutableAttributedString alloc] initWithString:self];
    if (color == nil) {
        color = [UIColor colorWithHexString:@"52c683"];
    }
    
    if (keyWords.length<=0) {
         return mutableAttributedStr;
    }
    
    for (NSInteger j=0; j<=keyWords.length-1; j++) {
        
        NSRange searchRange = NSMakeRange(0, [self length]);
        NSRange range;
        NSString *singleStr = [keyWords substringWithRange:NSMakeRange(j, 1)];
        while
            ((range = [self rangeOfString:singleStr options:0 range:searchRange]).location != NSNotFound) {
                //改变多次搜索时searchRange的位置
                searchRange = NSMakeRange(NSMaxRange(range), [self length] - NSMaxRange(range));
                //设置富文本
                [mutableAttributedStr addAttribute:NSForegroundColorAttributeName value:color range:range];
                
            }
    }
    
    return mutableAttributedStr;
    
    
    
}

swift 版本

extension String{
    
    func keyWords_swift(_ keyWords: String, withKeyWordsColor color: UIColor = .red) -> NSMutableAttributedString? {
        
        let mutableAttributedStr = NSMutableAttributedString.init(string: self)
        if keyWords.isEmpty {
            return mutableAttributedStr
        }
        let text = NSString.init(string: self)
        var range = text.range(of: keyWords)
        
        var searchRange = NSMakeRange(0, self.count);
        
        while range.location != NSNotFound {
            mutableAttributedStr.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: range)
            //改变多次搜索时searchRange的位置
            searchRange = NSMakeRange(NSMaxRange(range), self.count - NSMaxRange(range));
            range = text.range(of: keyWords, options: [], range: searchRange)
        }
        
        return mutableAttributedStr
    }
    
    func keyWords_swiftNormal(_ keyWords: String, withKeyWordsColor color: UIColor = .red) -> NSMutableAttributedString? {
        
        let mutableAttributedStr = NSMutableAttributedString.init(string: self)
        if keyWords.isEmpty {
            return mutableAttributedStr
        }
        let text = NSString.init(string: self)
        let range = text.range(of: keyWords)
        if range.location != NSNotFound {
             mutableAttributedStr.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: range)
        }
        
        return mutableAttributedStr
    }
}

func range(from nsRange: NSRange) -> Range<String.Index>? {
            guard
                let from16 = utf16.index(utf16.startIndex, offsetBy: nsRange.location, limitedBy: utf16.endIndex),
                let to16 = utf16.index(from16, offsetBy: nsRange.length, limitedBy: utf16.endIndex),
                let from = String.Index(from16, within: self),
                let to = String.Index(to16, within: self)
                else { return nil }
            return from ..< to
        }
    func nsRange(from range: Range<String.Index>) -> NSRange {
            let from = range.lowerBound.samePosition(in: utf16)!
            let to = range.upperBound.samePosition(in: utf16)!
            return NSRange(location: utf16.distance(from: utf16.startIndex, to: from),
                           length: utf16.distance(from: from, to: to))
        }


func getMoreKeyWordsAttributedString(members: (keywrod:String,color:UIColor)...) ->NSMutableAttributedString {
        let mutableAttributedStr = NSMutableAttributedString.init(string: self)
        if members.isEmpty {
            return mutableAttributedStr
        }
        for i in members {
            let keywrod = i.keywrod
            let color = i.color
            if keywrod.isEmpty {
                continue
            }
            
            let text = NSString.init(string: self)
            var range = text.range(of: keywrod)
            var searchRange = NSMakeRange(0, self.count);
            while range.location != NSNotFound {
                mutableAttributedStr.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: range)
                //改变多次搜索时searchRange的位置
                searchRange = NSMakeRange(NSMaxRange(range), self.count - NSMaxRange(range));
                range = text.range(of: keywrod, options: [], range: searchRange)
            }
            
        }
        
        return mutableAttributedStr
    }

剩下看demo 吧