先前的问题：从Appdelegate访问另一个类中的UILabel

Question

I have a method that that subtracts 2 from an int "healthInt". Then after that i have an NSString called "healthString" which will just display "healthInt". So what I wanna do in this method "take2Damage" is subtract 2 from "healthInt". then set a UILabel called "healthLabel" to healthString. the problem is healthLabel is located in another class. Here's some code.

Appdelegate.m

-(void)take2Damage{
healthInt = healthInt - 2;

}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:        (NSDictionary *)launchOptions
{
healthInt = 100;
healthString = [[NSString alloc]initWithFormat:@"%d", healthInt];

LevelOneViewController.m

IBOutlet UILabel * healthLabel;

Since the last person didn't know what i meant, i thought i'd clarify. I want code that i can put in the take2Damage to access a UILabel from another class. If that isn't possible then i would like code to access the healthInt variable from another file. Hopefully this will work thanks.

Answer 1

First, do not modify the IBOutlets of another class. This is very error prone because of how IBOutlets are managed by UIViewController .

Next, your basic issue is that you're not following the MVC pattern (Model-View-Controller). Something like "health" should be stored in a model object such as a "Player" class. The AppDelegate does not take damage. The Player takes damage. Then the view displays the current value of player.health .

To get an overview of MVC, see the Cocoa Core Competencies docs (be sure to follow the links). MVC is the heart of Cocoa development. Make sure you understand it before going too far.

Also useful: Organizing iOS project for MVC design pattern

And some good example code showing a well-designed MVC app: The Elements .

You will probably have further questions after you read the above, but start by reading up on the basic architecture of Cocoa. Then it should be more clear how objects interact with each other.