NSString 详解

NSString 详解

-(void)test{// 定义常量字符串    NSString *str1 = @"常量字符串";    NSLog(@"str1 : %@",str1);    // 空字符串    NSString *str2 = [[NSString alloc] init];    NSString *str3 = [NSString string];    NSLog(@"str2 : %@",str2);    NSLog(@"str3 : %@",str3);    // 格式化字符串    NSString *str4 = [[NSString alloc] initWithFormat:@"%2f",32.1F];    NSString *str5 = [NSString stringWithFormat:@"%d",29];    NSLog(@"str4 : %@",str4);    NSLog(@"str5 : %@",str5);    // 比较字符串内容和对象    NSString *str6 = @"aaa";    NSString *str7 = [[NSString alloc] initWithFormat:@"aaa"];    if ([str6 isEqualToString:str7]) {        NSLog(@"content str6 equals str7");    }else{        NSLog(@"content str6 is not equals str7");    }    if (str6 == str7) {        NSLog(@"same str6 and str7");        NSLog(@"str6 address : %p str7 address:%p",str6,str7);    }else{        NSLog(@"not same str6 and str7");        NSLog(@"str6 address : %p str7 address:%p",str6,str7);    }    //比较字符串大小（忽略大小写）    NSString *str8 = @"e";    NSString *str9 = @"D";    NSComparisonResult result = [str8 caseInsensitiveCompare:str9];    // 1 为降序 0 为升序    NSLog(@"compare result : %ld",(long)result);    // 转换为基本数据类型    NSString *str10 = @"5.98";    NSLog(@"boolValue : %d",[str10 boolValue]);    NSLog(@"floatValue :%f",[str10 floatValue]);    NSLog(@"doubleValue: %f",[str10 doubleValue]);    NSLog(@"intValue:%d",[str10 intValue]);    // 字符串转换    NSString *str11 = @"hEllo iOs";    NSLog(@"upper:%@",[str11 uppercaseString]);// 大写    NSLog(@"lower:%@",[str11 lowercaseString]);// 小写    NSLog(@"capitalized :%@",[str11 capitalizedString]);// 首字母大写    // 字符串转换成数组    NSString *str12 = @"abc 123 def 456 ghi 789";    NSArray *array = [str12 componentsSeparatedByString:@" "];    NSLog(@"array : %@",array);    // 截取字符串    NSString *str13 = @"0123456789";    // 从第i索引开始截取到末尾    NSLog(@"subStringFromIndex :%@",[str13 substringFromIndex:3]);    // 从索引0开始截取到i索引(不包括i索引)    NSLog(@"subStringToIndex : %@",[str13 substringToIndex:4]);    // 从第i索引开始截取长度为L的字符串    NSRange range = NSMakeRange(2, 3);//    NSRange range = {2,3};    NSLog(@"range: %@",[str13 substringWithRange:range]);    // 字符串拼接    NSString *str14 = @"abc";    NSString *str15 = @"123";    NSLog(@"append string : %@ ",[[str14 stringByAppendingString:str15] stringByAppendingString:str14]);    // 查找字符串    NSString *str16 = @"adfasd367890b2342_af+=234";    NSRange range1 = [str16 rangeOfString:@"67890"];    if (range1.location == NSNotFound) {        NSLog(@"string no found");    }else{        NSLog(@"range1 %@",NSStringFromRange(range1));    }    // 可变字符串    NSMutableString *mutableString1 = [[NSMutableString alloc] initWithString:@"123abc"];    [mutableString1 insertString:@"fff" atIndex:3];    NSLog(@"insertString : %@",mutableString1);    // 替换    [mutableString1 replaceCharactersInRange:NSMakeRange(3, 3) withString:@"xxx"];    NSLog(@"replace : %@",mutableString1);    // 删除    [mutableString1 deleteCharactersInRange:NSMakeRange(3, 3)];    NSLog(@"delete :%@",mutableString1);}

运行结果如下：

str1 : 常量字符串str2 : str3 : str4 : 32.099998str5 : 29content str6 equals str7not same str6 and str7str6 address : 0xe30c4 str7 address:0x7b6f24a0compare result : 1boolValue : 1floatValue :5.980000doubleValue: 5.980000intValue:5upper:HELLO IOSlower:hello ioscapitalized :Hello Iosarray : (    abc,    123,    def,    456,    ghi,    789)subStringFromIndex :3456789subStringToIndex : 0123range: 234append string : abc123abc range1 {7, 5}insertString : 123fffabcreplace : 123xxxabcdelete :123abc