objective c calling method inside own instance

Question

Really new with objective c (building iphone app) and I'm trying to figure out how to properly understand how calling methods work (compared to c#, the most recent language I've been working with)

I have this implementation

@interface User : NSObject{
}

@property NSInteger Id;
@property NSString *email, *password;
-(BOOL)isValid;
@end

@implementation User

-(BOOL)isValid{
  NSString *password = self.validateString:self.password;
  NSString *email = self.email;

  if(validUser){
     return YES;
  }else{
     return NO;
  }
}

EDIT: SOrry if it wasn't clear but this is the method I'm trying to call.

-(NSString *)validateString:(NSString *)string{
    // process the string
    return @"";
}

Basically I'm trying to create an instance in my view onclick of a button like so:

- (IBAction)btnSubmit:(id)sender {
    // get values of email and password

    // do an isvalid to check with web service.
    User *user = [[User alloc] init];
    user.email = @"email@email.com";
    user.rawPassword = @"pass";

    if(user.isValid){
        // go to next page
    }
    else{
        // else refresh current page
    }
}

Is creating the instance on click and then passwing the values to process inside the instance a good practice?

Thanks!

Answer 1

No need of creating it's own object there. You can use the current object for doing this:

- (IBAction)btnSubmit:(id)sender
  {    
    self.email = @"email@email.com";
    self.rawPassword = @"pass";

    if(self.isValid)
    {
        // go to next page
    }
    else
    {
        // else refresh current page
    }
}

You can refer to same object within its scope using self keyword. It's similar to this keyword used in C++

Answer 2

I'm not sure which methods you are trying to call within the object but to call a method in the current object you use self .

ie

[self runSomeFunction];

Answer 3

Use

Note:- If you are creating a button actiion in same class then there is no need to create an instance of same class , you can use self

  - (IBAction)btnSubmit:(id)sender {
// get values of email and password

// do an isvalid to check with web service.
 User *user = [[User alloc] init];//not need if its same user class

user.email = @"email@email.com";//self.email=@"email@email.com"; if same user class

user.rawPassword = @"pass";//self.rawPassword=@"pass"; if same user class



if([self isValid]){//made a change here as in objective c its a syntax to call a method not with "."
    // go to next page
}
else{
    // else refresh current page
}
}

Answer 4

That depens on whether you really need to alloc a new instance which we cannt say because that depends on your business logic.

If you would crate a new instance in c++ here with new, then yes, alloc/init a new instance and use it.

If you would refer to this in c++, as your questiont title suggests, then you can use self quite corresponding to this . self.isValid and [self isValid] are equivalents.

This is for instance methods. Within class methods self would refer to the class, not the instance