Object-C之NSString

1.去掉左右两边的空格；

NSString *str = @" 正文内容，头部尾部带有空格 ";    

NSString *dealtStr = [str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

2.替换某个字符串中的所有符合条件的字符

NSString *str = @" 正文内容，头部尾部带有空格 ";
    
NSString *dealtStr = [str stringByReplacingOccurrencesOfString:@" " withString:@"XXX"];

//NSLog : XXX正文内容，头部尾部带有空格XXX

3..截取字符串

NSString*string =@"www.ABCDEFGHIJKLMN.com.cn";
//取0~第7-1个
NSString *string1 = [string substringToIndex:7];
NSLog(@"%@",string1);
//取第7个~结尾
NSString *string2 = [string substringFromIndex:7];
NSLog(@"%@",string2);
//取第4个后面的长度为2的字符
NSString *string3 = [string substringWithRange:NSMakeRange(4, 2)];
NSLog(@"%@",string3);

//输出:
2016-08-08 16:49:24.061 宏定义的黑魔法[4125:213926] www.ABC
2016-08-08 16:49:24.062 宏定义的黑魔法[4125:213926] DEFGHIJKLMN.com.cn
2016-08-08 16:49:24.062 宏定义的黑魔法[4125:213926] AB

4.匹配字符串

NSString*string =@"www.ABCDEFGHIJKLMN.com.cn";   

//判断字符串是否包含字符串，可以用来判断文件类型
if ([string hasPrefix:@"www."]) {//前
    NSLog(@"字符串前面包含(www.)");
}

if ([string hasSuffix:@".com.cn"]) {//后
    NSLog(@"字符串后面包含(.com.cn)");
}

if ([string rangeOfString:@"ABC"].location != NSNotFound) {
    NSLog(@"这个字符串中有ABC");
}

//输出：
2016-08-08 16:55:31.014 宏定义的黑魔法[4295:221147] 字符串前面包含(www.)
2016-08-08 16:55:31.014 宏定义的黑魔法[4295:221147] 字符串后面包含(.com.cn)
2016-08-08 16:55:31.014 宏定义的黑魔法[4295:221147] 这个字符串中有ABC

5.分隔字符串

NSString *string = @"www.&A&B&C&D&E&F&G";
//将字符串以“&”为分割线，分割成数组
NSArray *separateElementsArray = [string componentsSeparatedByString:@"&"];
NSLog(@"\n%@",separateElementsArray);
//将数组元素拼接成字符串
NSString *string1 = [separateElementsArray componentsJoinedByString:@""];
NSLog(@"%@",string1);

//输出：
2016-08-08 17:04:29.913 宏定义的黑魔法[4470:229085] 
(
    "www.",
    A,
    B,
    C,
    D,
    E,
    F,
    G
)
2016-08-08 17:04:29.913 宏定义的黑魔法[4470:229085] www.ABCDEFG

6

提取字符串中的纯数字.png

- (NSMutableAttributedString*)charactersString:(NSString*)str{
    
    //纯数字，数组
    NSMutableArray *stringValueArray = [NSMutableArray array];
    
    NSMutableArray *characters = [NSMutableArray array];
    
    NSMutableString *mutStr = [NSMutableString string];
    
    //分离出字符串中的所有字符，并存储到数组characters中
    for (int i = 0; i < str.length; i ++) {
        
        NSString *subString = [str substringToIndex:i + 1];
        
        subString = [subString substringFromIndex:i];
        
        [characters addObject:subString];
    }
    
    //利用正则表达式，匹配数组中的每个元素，判断是否是数字，将数字拼接在可变字符串mutStr中
    for (NSString *b in characters) {
        
        NSString *regex = @"^[0-9]*$";
        
        NSPredicate *pre = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];// 谓词
        
        BOOL isShu = [pre evaluateWithObject:b];// 对b进行谓词运算
        
        if (isShu) {
            
            [mutStr appendString:b];
        } else {
            
            if (mutStr.length>0) {
                
                [stringValueArray addObject:mutStr];
                
                mutStr  = [NSMutableString string];
            }
        }
    }
    
    //此处已经将纯数字提取出来成功，
    //NSLog(@"字符串(数字)数组：%@",stringValueArray);
    
    //改变颜色
    NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc]initWithString:str];
    
    [stringValueArray enumerateObjectsUsingBlock:^(NSString * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        
        NSRange range = [str rangeOfString:obj];
        
        [attributeString addAttribute:NSForegroundColorAttributeName
                       value:[UIColor redColor]
                       range:NSMakeRange(range.location, range.length)];
    }];
    
    return attributeString;
}

• 用法实例：

- (void)viewDidLoad {
    
    [super viewDidLoad];

    NSString *str = @"您的房源挂牌价格已经由250万调整为240万";
    
    _elblTitle.attributedText = [self charactersString:str];
}

提取字符串中的纯数字.png