OC——NSString和NSMutableString

int main(int argc, const char * argv[])
{

    @autoreleasepool {

        //----------------NSString-----------------------------
        NSString *str1 = @"这是一个字符串常量";
        NSLog(@"str1 = %@",str1);
        //创建一个空字符串
        NSString *str2 = [[NSString alloc]init];
        NSString *str3 = [NSString string];
        NSLog(@"str2 = %@",str2);
        NSLog(@"str3 = %@",str3);
        //快速创建一个字符串
        NSString *str4 = [[NSString alloc]initWithString:str1];
        NSString *str5 = [NSString stringWithString:str1];
        NSLog(@"str4 = %@",str4);
        NSLog(@"str5 = %@",str5);
        //创建一个格式化字符串
        NSString *str6 = [[NSString alloc]initWithFormat:@"%d",10];
        NSString *str7 = [NSString stringWithFormat:@"%.2f",10.8099887];
        NSLog(@"str6 = %@",str6);
        NSLog(@"str7 = %@",str7);

        //比较两个字符串内容是否相等
        if ([str6 isEqualToString:str7]) {
            NSLog(@"str6 is EqualToString str7");
        }else{
            NSLog(@"str6 is not EqualToString str7");
        }

        //转换为基本数据类型
        NSString *str8 = @"3";
        float f1 = [str8 floatValue];
        NSLog(@"str8 = %.2f",f1);

        //字符串拆分为数组
        NSString *str9 = @"命 运 就 算 颠 沛 流 离";
        NSArray *array = [str9 componentsSeparatedByString:@" "];
        NSLog(@"array = %@",array);
        NSLog(@"array[0] = %@",array[0]);

        //截取字符串
        NSString *str10 = @"123456789";
        NSString *subStr1 = [str10 substringToIndex:4];
        NSString *subStr2 = [str10 substringFromIndex:6];
        NSLog(@"subStr1 = %@",subStr1);
        NSLog(@"subStr2 = %@",subStr2);

        NSRange range = {4,2};
        NSString *subStr3 = [str10 substringWithRange:range];
        NSLog(@"subStr3 = %@",subStr3);

        //拼接字符串
        NSString *str11 = @"123";
        NSString *str12 = @"456";
        NSString *appStr1 = [[NSString alloc]initWithFormat:@"%@%@",str11,str12];
        NSString *appStr2 = [str11 stringByAppendingFormat:@"%@",str12];
        NSString *appStr3 = [str11 stringByAppendingString:str12];
        NSLog(@"appStr1 = %@",appStr1);
        NSLog(@"appStr2 = %@",appStr2);
        NSLog(@"appStr3 = %@",appStr3);

        //查找字符串
        NSString *str13 = @"qweradsfzxcvqazxsw";
        NSRange range1 = [str13 rangeOfString:@"dsfzx"];
        NSLog(@"%@",NSStringFromRange(range1));
        NSLog(@"%d",range1.location);
        if (range1.location != NSNotFound) {
            NSLog(@"str found");
        }else{
            NSLog(@"str not found");
        }

        /*------------NSMutableString 可变字符串-----------------*/
        //插入
        NSMutableString *mStr1 = [[NSMutableString alloc] initWithFormat:@"abcd"];
        [mStr1 insertString:@"defg" atIndex:4];    //注意：此处为在源字符串上修改，并未生成新的字符串
        NSLog(@"mStr1 = %@",mStr1);

        //替换
        [mStr1 replaceCharactersInRange:NSMakeRange(4, 4) withString:@"1234"];
        NSLog(@"%@",mStr1);

        //删除
        [mStr1 deleteCharactersInRange:NSMakeRange(4, 4)];
        NSLog(@"%@",mStr1);
    }
    return 0;
}