OOP In Objective-C - objective-c

Question

I am familiar with OOP as I have been coding in Java for a while now, but I am having (syntax?) trouble in Objective-C. I have been looking at other posts on here but nothing has helped so far.
I have a class named "Play_Name.m" that has a method that sets a players name at the touch of a button and another method that gets the name and returns a string, (NSString*)get_name. I also have another class named "Play_ChooseChar.m" which is supposed to display the name entered in by calling the get_name function.
get_name returns the correct name when I call it in "Play_Name" (it's owner), but when I call it in "Play_ChooseChar" it returns (null).
//Play_Name code below
#import "Play_Name.h"
#interface Play_Name ()
#end
#implementation Play_Name
#synthesize playerName;
#synthesize textName;
-(IBAction)set:(id)sender {
[self setPlayerName:(self.textName.text)];
if([self.textName.text length] <= 0) {
playerName = #"Player";
NSLog(#"YOUR NAME: %#", playerName);
}
NSLog(#"YOUR NAME: %#", playerName);
}
//...........
#end
//Play_ChooseChar code below
#import "Play_ChooseChar.h"
#import "Play_Name.h"
#interface Play_ChooseChar ()
#end
#implementation Play_ChooseChar
#synthesize display_name;
#synthesize playname;
#synthesize boy;
#synthesize girl;
#synthesize isGirl;
#synthesize isBoy;
bool isGirl = FALSE;
bool isBoy = FALSE;
-(void)theName {
Play_Name *pN = [[Play_Name alloc] init];
[pN setPlayerName: pN.playerName];
NSLog(#"NAME: %#", pN.playerName);
self.display_name.text = pN.playerName;
//display_name.text = #"test";
[pN release];
//............
#end
So when I run it and enter my name, the print statement from "Play_ChooseChar" returns 'NAME: (null)'

Answer 1

Opening lecture: you seem to be throwing Objective-C conventions to the wind. Getters shouldn't refer to the act of getting — so you'd implement name, not get_name and almost the only verb you'll see is 'is', in the sense of isValid ala NSTimer. Objective-C also uses camel case, starting with a lower-case character so player_name should be playerName. Similarly your class should have a three-letter prefix (as Objective-C doesn't do namespaces) and also be camel case, e.g. ATPPlayName.
Lecture points aside, this:
Play_Name *play_name = [[Play_Name alloc] init];
creates a brand new instance of Play_Name. It's not the same as whatever instance you're using elsewhere. That instance doesn't have a name attached yet. So when you ask it for the name in the next line, it's nil.

Answer 2

You haven't really shown enough code to determine the problem. However, I would recommend using properties rather than methods which follow your own naming convention. For example:
#interface Player: NSObject
#property NSString* name;
#property NSString* character;
#end
The above defines a class Player with the properties name and character. Xcode will generate the appropriate accessor methods and instance variables that 'back' these properties. See the language reference for more details.

Answer 3

You should create properties, and xcode will automatically create getter & setter for you.
Have a look here:

Answer 4

putting design and code conventions aside:
when you create a new Play_Name instance, its get_name will return nil, obviously, because nowhere in the code have you called set_name before calling get_name.
You should first do:
[play_name set_name:#"john"];
And, assuming your set_name method is implemented correctly, [play_name get_name] should then return the correct value.
I second the others who recommend to use properties since it takes care of most memory mgmt nuances for you. You can read more about this here:
Objective-C: Declared Properties