Calling a method from an owned object on the owner

I have a table view class called RootViewController and a class providing WiFi functionality called WifiClass. When I load the RootViewController class, I am calling a method named setup on WifiClass, which will do the Wifi connection initialization.

While the app is running, if any connected device sends some data to my device, there is a stream handler delegate in the Wifi class which will trigger. At that time, I need to call a method named myMethod from my RootViewController. Please can anyone tell me a good way to开发者_C百科 do this properly?

There a different conceptes in Objective-C like

• Delegates
• Notifications
• Key-Value-Observing

I'm assuming you mean the stream handler is a delegate of the WifiClass? In that case, set your RootViewController as the delegate of the WifiClass. In the delegate callback, implemented in RootViewController, call myMethod in RVC:

// RootViewController.m
- (void)delegateCallback {
    [self myMethod];
}

Response to comments: In your WifiClass, you'll have to create an instance variable for the delegate.

@protocol WifiStreamDelegate
- (void)handleNewStream:(id)someStreamObject;
@end

@interface WifiClass : NSObject {
    // *delegate* is an object that conforms to the WifiStreamDelegate protocol
    id<WifiStreamDelegate> delegate;
    // …Other instance variables    
}
// You don't want to own your delegate
// Use the *assign* flag
@property (nonatomic, assign) id<WifiStreamDelegate> delegate;
// …Other properties

@end

@implementation WifiClass
@synthesize delegate;
// …Other methods
@end

Then in your RootViewController, you have to implement the delegate and hook things up:

#import "WifiClass.h"
@interface RootViewController : UITableViewController<WifiStreamDelegate>
{
    WifiClass *wifi;
    // …Other instance variables
}
// *wifi* is now an object you own—retain it
@property (nonatomic, retain) WifiClass *wifi
// …Other properties
@end

@implementation RootViewController
@synthesize wifi;

- (id)initWithCoder:(NSCoder *)aDecoder {
    if (!(self = [super initWithCoder:aDecoder]))
        return nil;
    if (!self.wifi)
        wifi = [[WifiClass alloc] init];
    // Set delegate
    wifi.delegate = self;
}

- (void)myMethod {
    // Do something
}

// Delegate method
- (void)handleNewStream:(id)someStreamObject {
    // Handle stream
    [self myMethod];
}
@end

Hope this helps!

Try this

[[UIApplication sharedApplication] sendAction:@selector(yourMethod) to:nil from:self forEvent:someEvent];

There are few things you can do. One is to have a weak reference to the object whose method you want to invoke. In this case the view controller is the object. Declare an assign-able property of the MainViewController (assuming this is the class) in the wifi class and set it to the view controller during initialization. Since you've a reference to the view controller, you can invoke the method you want in the delegate method.

Another approach is to use Blocks. The block's definition can be -

typedef void (^UpdateHandler)(void);

...

@interface WiFiConnection:NSObject <...> {
    ...
    UpdateHandler updateHandler;
}
...
- (void)setUpdateHandler:(UpdateHandler)handler;
@end

@implemention WiFiConnection
...
- (void)setUpdateHandler:(UpdateHandler)handler {
    updateHandler = handler;
}
...
- (void)delegateMethodFromWhichYouWantToInvoke {
    ...
    if ( updateHandler != NULL ) {
        dispatch_async(dispatch_get_main_queue(), updateHandler);
    }
}
...
@end

You can now pass the update block during initialization,

WiFiConnection *connection = [[WiFiConnection alloc] init];
...
__block MainViewController *controller = self;
[connection setUpdateHandler:^{
    [controller welcomeMessage];
}];

There is probably a lot in there. Let me know if it is still unclear. Read up on GCD. It is a very powerful tool in my opinion.

just send an notification......

post it like this...

[[NSNotificationCenter defaultCenter] postNotificationName:@"MyMethodNotification" object:self];

receive it like this...

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(MyMethod:) name:@"MyMethodNotification" object:nil];

your method....

• (void)MyMethod:(NSNotification *)notification { .... .... .... ur code }

remove it

[[NSNotificationCenter defaultCenter] removeObserver:self];

Why not move the welcomemessage method to the appDelegate. This would make more sense as I assume the "message" does not need to be associated with any particular view Controller.

So when your wifi delegate is triggered just reference the appDelegate and call the method:

[[[UIApplication sharedApplication] delegate] welcomeMessage];