NSString：可以保存字符串。

創(chuàng)建NSString實(shí)例：

1. NSString *lament = @"Why me!?";(并沒有明確地發(fā)送消息給NSString類，@"..." 是Objective-C語言中的一個(gè)縮寫，代表根據(jù)給定的字符串創(chuàng)建一個(gè)NSSTring對(duì)象，這種縮寫稱為字面量語法(literal syntax)，該實(shí)例稱為NSString的字面量實(shí)例(NSString字面量)。)
2. 創(chuàng)建動(dòng)態(tài)字符串：NSString *dateString = [NSString stringWithFormat:@"The date is %@",now];(類似于NSLog())
3. NSString實(shí)例可以保存任意Unicode字符。如果需要插入非ASCII碼字符，則可以使用\u，后面加上該字符的十六進(jìn)制Unicode編碼。如：NSString *slogan = @"I \u2661 New York!";

NSString常用方法：

1. length方法：-(NSUInteger)length （獲取字符串中字符的數(shù)量）。如：

   //-(NSUInteger)length
   NSUInteger charCount = [dateString length];
   

2. isEqualToString:方法：-(Bool)isEqualToString:(NSString *)other; (查看一個(gè)字符串是否和另一個(gè)字符串相等)。如：

   //-(Bool)isEqualToString:(NSString *)other
   if([slogan isEqualToString:lament]) {
      NSLog(@"%@ and %@ are equal",slogan,lament);
   }
   

3. uppercaseString方法：-(NSString *)uppercaseString;（把一個(gè)字符串變成大寫形式）

   //-(NSString *)uppercaseString;
   NSString *angryText = @"That makes me so mad!";
   BSString *reallyAngryText = [angryText uppercaseString];
   

4. 查找字符串

//- (NSRange)rangeOfString:(NSString *)searchString
NSString *listOfName = @"...";//名單
NSString *name = @"ward";
NSRange match = [listOfName rangeOfString:name];
if (match.location == NSNotFound) {
NSLog(@"no match found");
} else {
NSLog(@"match found");
}

5.  合并字符串
```js
//- (NSString *)stringByAppendingString:(NSString *)aString;
NSString *one = @"one and ";
NSString *two = @"two";
NSString *methodd = [one stringByAppendingString:two];
NSLog(@"%@",methodd);