初学objective c语言6 number string

oc里面都是采用对象:

NSNumber *num = @123;

NSLog(@"%@",num);          //把123存到num里面

NSNumber *num1 =[[NSNumber alloc] initWithInt:123];

NSNumber *num3 =[NSNumber numberWithInt:123];

 

        NSString *str1 = @"i";

        NSString *str2 = @"love";

        NSString *str3 = @"you";

        NSString *str = [str1 stringByAppendingFormat:@".%@.%@",str2 ,str3];  //将字符str1 str2 str3连接以 . ;

        NSLog(@"%@",str);

        NSString *fp = @"/users/apple/Desktop/test.plist";                           

        [str writeToFile:fp atomically:YES encoding:NSUTF8StringEncoding error:NULL];   //将str存到 /users/apple/Desktop/test.plist

        NSString *str4 = [NSString stringWithContentsOfFile:fp encoding:NSUTF8StringEncoding error:NULL];  //将str读出来

        NSArray *p = [str4 componentsSeparatedByString:@"."];    //以'.'分开;    oc字符数组 p;

        NSLog(@"%@", p );