无法使用委托

Question

I'm new to objective c and trying to grasp the delegate methology and usage. Currently i have Alertview class, and i need it to make a another class to call function of its. I'v managed to do the same with with appdelegate class. But can't do it with my own class.

                TableViewController *newControll = (TableViewController*)[UIApplication sharedApplication].delegate;
                [newControll openSettings];

That's how I'm trying to access my method. Compilator see's this method in newControll, yet calling this gets unrecognizet selector.

Basicaly i need to call a function of which was already created earlier, from another class. I'm sorry if this is a simple solution, but i just can't grasp delegate and objective-c quite well yet.

Maybe not everyone get's what I need to do, so i'll try to explain once more.

I have object TableViewController . From this object inside I'm calling class AlertView to display some alert message. And accordingly to user interaction in alert dialogs (password is ok, password isn't) I need to call method openSettings in my TableViewController or not call. So how to do this?

Answer 1

If your TableViewController is not your appdelegate class, you should use the object of TableViewController to use the method openSettings .

It should be something like,

TableViewController *newControll = [[TableViewController alloc] init];

Assuming that you are moving to a new alertView . In your AlertView.h file add,

@property(nonatomic, retain) TableViewController *tableViewController;

And while creating the new alertView object,

AlertView *alertView = [[AlertView alloc] init];
//some code..
alertView.tableViewController = self;

Now in your AlertView class, call it as,

[self.tableViewController openSettings];

Usage of appdelegate is not the way to do it.

If you need some tutorials on iOS, check raywenderlich .