I'm a beginner in iOS development. I have a custom view:
@interface MyView : UIView {
In the ViewController, I add this view as a subview (would be better to do in another way, maybe in the Storyboard?):
MyView *myView = [[MyView alloc]initWithFrame:myFrame];
[self.view addSubview:myView];
in it, I follow the touches on screen, and I have a touchesEnded method:
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
// myValue is a class variable of MyView
myValue = doSomething();
}
Now, how can I get the value of myValue
in the ViewController? Maybe a listener or a callback that can be invoked inside touchesEnded
in MyView?
Well, a simple way is to keep a reference to the view controller in MyView
, eg, define a property like:
@property (weak,nonatomic) MyViewController *viewController;
And then in the view controller assign myView.viewController = self
. This way you can then call whatever methods on the view controller from MyView
, eg, [viewController myView:self changedValue:myValue]
or whatever.
(And, yes, it's possible to add the custom view subclass directly in the storyboard. Just add a generic UIView
in the storyboard and change its class to MyView
.)
There are of course many alternative ways, eg, notifications, or simply polling a property of MyView
from the view controller if its only of interest at certain times, etc.
For instance, you can post a NSNotification in touchesEnded method of your view:
[[NSNotificationCenter defaultCenter] postNotificationName:@"ViewDidTouch" object:self];
Listen for this notification in your view controller. To achieve that add in the view controller's method viewDidLoad a line:
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onViewDidTouch:) name:@"ViewDidTouch" object:nil];
And then implement below method in your view controller:
- (void) onViewDidTouch:(NSNotification*)notification
{
// do something
}
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