创建一个字符串对象:
| 1 2 3 4 5 6 7 8 9 | NSstring * str1 = @ "hello" ; NSString * str = [[ NSString alloc]initWithString:@ "hello world!" ]; NSString * str_1 = [[ NSString alloc]initWithUTF8String: "hello world" ]; //把C的字符串转化为OC的字符串 int a = 123; NSString * str_3 = [[ NSString alloc]initWithFormat:@ "a = %d %s%@" , a, "abcd" , @ "efg" ]; //用格式化字符串初始化 //可完成字符串的拼接以及完成C的字符串与OC的字符串的转化 NSString * str1 = [ NSString stringWithString:@ "hello world" ]; NSString * str2 = [ NSString stringWithUTF8String: "hello world" ]; NSString * str3 = [ NSString stringWithFormat:@ "%s" , "hello world" ]; |
字符串转化:
| 1 2 3 4 5 6 7 | NSString * str = @ "hello" ; const char *p = [str UTF8String];将OC字符串转化为C的字符串 str = @ "123" ; int a = [str intValue]; //将数字串转化成整型数据 [str floatValue]; //将数字串转化成float型 [str doubleValue]; //将数字串转化成double型 |
常用的NSString Message(OC 的字符 :typedef unsigned short unichar)
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | NSLog (@ "%ld" ,[str1 length]); //求字符串长度 NSLog (@ "%c" , [str1 characterAtIndex:1]); //获取字符串中的字符 BOOL ret = [str1 isEqualTo:str2]; //比较两个字符串是否相等,相等返回YES(1),不相等返回NO(0) (BOOL YES(1) NO(0)) long ret1 = [str1 compare:str2]; //比较两个字符串的大小,str1大于 返回1 相等返回0 小于返回-1 long ret2 = [str1 caseInsensitiveCompare:str2]; //不区分大小写比较字符串大小 NSString * ptr = [str2 uppercaseString]; //将字符串中的所有小写字符转换成大写 不改变原来的字符串 ptr = [str1 lowercaseString]; //将字符串中的所有大写字符转换成小写 不改变原来的字符串 ptr = [str3 capitalizedString]; //将字符串中出现的第一个字母转换成大写，其余字母小写 NSString * str4 = @ "hello world" ; NSRange range = [str4 rangeOfString:@ "wr" ]; //查找子串，找不到返回NSNotFound 找到返回location和length if (range.location != NSNotFound ) { NSLog (@ "%ld %ld" ,range.location, range.length); } NSString * str5 = @ "helloworld" ; NSString * ptr1 = [str5 substringToIndex:4]; //字符串抽取 从下标0开始到4 不包括4 NSString * ptr2 = [str5 substringFromIndex:5]; //从下标5开始抽取到字符串结束 包括5 NSRange range1 = {4,3}; //结构体初始化 NSString * ptr3 = [str5 substringWithRange:range1]; //在range指定范围内抽取 NSString * ptr4 = [str5 substringWithRange: NSMakeRange (4,3)]; //NSMakeRange可以生成一个结构体 NSString * str = @ "www.1000phone.com" ; BOOL ret = [str hasPrefix:@ "www" ]; //判断字符串是否以指定字符串开头 NSString * str1 = @ "1.txt" ; BOOL ret1 = [str hasSuffix:@ ".txt" ]; //判断字符串是否以指定的字符串结尾 NSMutableString 可变字符串(动态增加和减少的) 继承于 NSString 可以使用 NSString 的所有方法 NSMutableString * str = [[ NSMutableString alloc]initWithString:@ "hello" ]; //将不可变的字符串转换为可变的字符串 [str insertString:@ "123" atIndex:1]; //在指定下标(不要越界)位置插入NSString类型字符串 [str appendString:@ "123" ]; //在字符串末尾追加字符串 [str deleteCharactersInRange: NSMakeRange (0, 2)]; //从指定下标删除length个字符 [str setString:@ "qianfeng" ]; //修改字符串亦称对该可变字符串赋值 [str replaceCharactersInRange: NSMakeRange (3, 1) withString:@ "ios" ]; //将指定下标位置的length个字符替换为指定的字符串
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