字符串与基本数据类型转换

    NSString *str1 = @"110";
    NSString *str2 = @"10";
    int res = str1.intValue + str2.intValue;
    NSLog(@"res = %i", res);

    NSString *str1 = @"110";
    NSString *str2 = @"10.1";
    double res = str1.doubleValue + str2.doubleValue;
    NSLog(@"res = %f", res);

   NSString *str = @"abc";
    const char *cStr = [str UTF8String];
    NSLog(@"cStr = %s", cStr);

    char *cStr = "abc";
    NSString *str = [NSString stringWithUTF8String:cStr];
    NSLog(@"str = %@", str);