assign is the correct annotation here. You use assign for any primitive types. The alternatives (weak, strong/retain) rely on the property pointing at an object to function. I believe the compiler won’t even let you declare the wrong type of property for this. If you really wanted to you could omit the assign as it … Read more
SEL is a type that represents a selector in Objective-C. The @selector() keyword returns a SEL that you describe. It’s not a function pointer and you can’t pass it any objects or references of any kind. For each variable in the selector (method), you have to represent that in the call to @selector. For example: … Read more
ex:- navigationItem.rightBarButtonItem = UIBarButtonItem(title: “Add”, style: .plain, target: self, action: #selector(addTapped))
You need to define the method in the target. Since you set the target as ‘self’, then yes that same object needs to implement the method. But you could have set the target to anything else you wanted. userInfo is a pointer that you can set to any object (or collection) you like and that … Read more
Yes, don’t add “()” if there is no param button.addTarget(self, action:#selector(handleRegister), for: .touchUpInside). and if you want to get the sender button.addTarget(self, action:#selector(handleRegister(_:)), for: .touchUpInside). func handleRegister(sender: UIButton){ //… } Edit: button.addTarget(self, action:#selector(handleRegister(_:)), for: .touchUpInside) no longer works, you need to replace _ in the selector with a variable name you used in the function … Read more
According to this documentation, the find method will search down through the tree of elements until it finds the element in the selector parameters. So $(parentSelector).find(childSelector) is the fastest and most efficient way to do this.
You can change the tint, quite easily in code via: ImageButton button = (ImageButton) this.findViewById(R.id.button_i_want_to_modify); button.setColorFilter(Color.argb(255, 255, 255, 255)); // White Tint
Try this code using VIewWillDisappear method to detect the press of The back button of NavigationItem: -(void) viewWillDisappear:(BOOL)animated { if ([self.navigationController.viewControllers indexOfObject:self]==NSNotFound) { // Navigation button was pressed. Do some stuff [self.navigationController popViewControllerAnimated:NO]; } [super viewWillDisappear:animated]; } OR There is another way to get Action of the Navigation BAck button. Create Custom button for UINavigationItem … Read more
This is a great question. Selector – a Selector is the name of a method. You’re very familiar with these selectors: alloc, init, release, dictionaryWithObjectsAndKeys:, setObject:forKey:, etc. Note that the colon is part of the selector; it’s how we identify that this method requires parameters. Also (though it’s extremely rare), you can have selectors like … Read more
Could you store strings and use NSSelectorFromString? From the docs NSSelectorFromString Returns the selector with a given name. SEL NSSelectorFromString ( NSString *aSelectorName );