常用的字符串处理方法

参考:

iOS开发宝典:String用法大全

加，剪，截，替，查 ,删
1.“加”
--

resultCode = [array componentsJoinedByString:@","];

这个用得挺多的，以某个特殊的符号（如@",")，把数组元素拼接一条字符串

而且数组元素里面不一定是NSString 类型喔
以下是测试：

//数组装了NSNumber类型的，貌似数组只能装类，不能直接装基本数据类型
    NSArray *arr = @[@(1),@(3)];
    NSString * test = @"";
    test = [arr componentsJoinedByString:@","];
    NSLog(@"___%@",test);

打印:

2016-03-18 10:13:34.259 test[4946:59102] ___1,3

1.1 在已有字符串后面添加字符

//appendString: and appendFormat:  
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];  
//[String1 appendString:@", I will be adding some character"];  
[String1  appendFormat:@"%@", [NSString stringWithFormat:@"%@\n",changeStr]];
*/  

1.2在已有字符串后面在所指定的位置中插入给出的字符串

//-insertString: atIndex:  
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];  
[String1 insertString:@"Hi! " atIndex:0];  
NSLog(@"String1:%@",String1);

2.“剪”

   self.test     = [[code componentsSeparatedByString:@"#"] firstObject];
    self.test = [[code componentsSeparatedByString:@"#"] lastObject];

componentsSeparatedByString
返回的是一个数组

另外

没有得“剪”，会保留原来的字符串的，所以大方的“剪”即可

3.查

    NSString *string1 = @"This is a string";  
    NSString *string2 = @"string";  
    NSRange range = [string1 rangeOfString:string2];  
    int location = range.location;  
    int leight = range.length;  
    NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];  
    NSLog(@"astring:%@",astring);  

NSString *str1 = @"can you \n speak English";  
    NSString *str = @"\n";  
    //在str1这个字符串中搜索\n，判断有没有  
    if ([str1 rangeOfString:str].location != NSNotFound) {  
        NSLog(@"这个字符串中有\n");  
    }  
    //rangeOfString 前面的参数是要被搜索的字符串，后面的是要搜索的字符  
    //NSNotFound 表示请求操作的某个内容或者item没有发现，或者不存在 

    //01：检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString *) aString;  
    NSString *String1 = @"NSStringInformation.txt";  
    [String1 hasPrefix:@"NSString"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");  
    [String1 hasSuffix:@".txt"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");  

当然写法是很灵活的比如：

//是否包含其它字符 
NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];  
Boolean contains = [astring rangeOfString:@”This”].length>0;

ps:rangeOfString这个方法有遍历的意思，但是不得不吐槽的是拿到的range.location还有用，但是range.length这个只能拿到该搜索字符串的长度，貌似真没啥用出

4.截

包括：4.1 截到那里（to);
4.2从哪里开始截取（from)；
4.3 截取的范围（range）；

    //-substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符  
    NSString *string1 = @"This is a string";  
    NSString *string2 = [string1 substringToIndex:3];  
    NSLog(@"string2:%@",string2);

    //-substringFromIndex: 以指定位置开始（包括指定位置的字符），并包括之后的全部字符  
    NSString *string1 = @"This is a string";  
    NSString *string2 = [string1 substringFromIndex:3];  
    NSLog(@"string2:%@",string2); 

    //-substringWithRange: //按照所给出的位置，长度，任意地从字符串中截取子串  
    NSString *string1 = @"This is a string";  
    NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];  
    NSLog(@"string2:%@",string2); 

特定字符串之间截取

    NSString *string1 = @"This is a string";
    NSRange end = [string1 rangeOfString:@"string"];
    NSRange start = [string1 rangeOfString:@"This"];


    NSString *string2 = [string1 substringWithRange:NSMakeRange(start.location, end.location)];
    NSLog(@"string2:%@",string2);

5.替

NSString *strUrl = [urlString stringByReplacingOccurrencesOfString:@" " withString:@""];  去掉空格

NSString *strUrl = [urlString stringByReplacingOccurrencesOfString:@" " withString:@"/"];替换字符

- (void)viewDidLoad
{
    [super viewDidLoad];
 
    NSString *str0 = @"中文my name is xuanyusong";
    NSString *temp = @"is";
    NSRange rang = [str0 rangeOfString:temp];
 
    NSLog(@"搜索的字符串在str0中起始点的index 为 %d", rang.location);
    NSLog(@"搜索的字符串在str0中结束点的index 为 %d", rang.location + rang.length);
 
    //将搜索中的字符串替换成为一个新的字符串
    NSString *str = [str0 stringByReplacingCharactersInRange:rang withString:@"哇咔咔卡卡咔"]; 
    NSLog(@"替换后字符串为%@", str);
 
    //将字符串中" " 全部替换成 *
    str = [str0 stringByReplacingOccurrencesOfString :@" " withString:@"@"]; 
    NSLog(@"替换后字符串为%@", str);
 
}

"CharactersInRange"和"OccurrencesOfString"都是替换，区别，"CharactersInRange"是目标范围替换，"OccurrencesOfString"是全替

举个例子：电话号码的星号替换

//substringWithRange:NSMakeRange(3,4)    从第三位开始截取四个字符
    NSString *a = @"13781213137";
    NSString *string=[a stringByReplacingOccurrencesOfString:[a substringWithRange:NSMakeRange(3,4)]withString:@"****"];
    NSLog(@"b:%@",string);

Log：

b:137****3137

还有就是借助NSScanner来替

- (NSString *)filterHTML:(NSString *)html
{
    NSScanner * scanner = [NSScanner scannerWithString:html];
    NSString * text = nil;
    while([scanner isAtEnd]==NO)
    {
        [scanner scanUpToString:@"<" intoString:nil];
        [scanner scanUpToString:@">" intoString:&text];
        html = [html stringByReplacingOccurrencesOfString:[NSString stringWithFormat:@"%@>",text] withString:@""];
    }
    return html;
}

6.删

在已有字符串中按照所给出范围和长度删除字符

//deleteCharactersInRange:  
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];  
[String1 deleteCharactersInRange:NSMakeRange(0, 5)];  
NSLog(@"String1:%@",String1);