touchesBegan没有回应

Question

I'd like to use the touchesBegan method to know when the user is taping somewhen outside of a UITextField in my TableView.

I've got a UIView that contains a TableView, and I have the following method :

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

NSLog(@"See a tap gesture");
UITouch *touch = [touches anyObject];
if(touch.phase==UITouchPhaseBegan){
    //find first response view
    for (UIView *view in [self.view subviews]) {
        if ([view isFirstResponder]) {
            [view resignFirstResponder];
            break;
        }
    }
}


[super touchesBegan:touches withEvent:event];

}

My self.view and my self.tableView have both the userInteractionEnabled set to YES, but for some reason, touchesBegan is never triggered. Any idea?

Answer 1

If your UIView contains your UITableView , then the table view is at the top of the responder chain and the touch events won't make it into your view. But there might be a better way to do this. What are you after?

UPDATE

Implement UITextFieldDeletate 's textFieldShouldReturn: method to intercept a press of 'Return':

-(BOOL)textFieldShouldReturn:(UITextField *)textField {
   [textField resignFirstResponder];
   return YES;
}

Also, a UITableViewDelegate is a UIScrollViewDelegate, so you can hook into those methods to determine when the user interacts with the table view.

Generally speaking I think you don't have to worry about dismissing the keyboard immediately when a user touches outside of it, especially if you have other text inputs on the same screen.

MOAR

Ok, fair enough, but things start to get complex when you intercept touch events via composite transparent views (these can get expensive as well), and so on. And you never know the repercussions that will arise down the road, not only for the user but for you the programmer when you want to upgrade the app in the future.

Why not keep it simple? How about just a 'Done' UIBarButtonItem , or a little translucent UIToolbar that slides up on top of the keyboard/picker ala Mobile Safari? These solutions are acceptable to the user, and can wind up making his life easier. They certainly make development easier by separating artifacts and functionality into modular units.

One final note

Using UITapGestureRecognizer I think will be difficult to get right in your situation. I'm worried that any tap recognizer you add to the table view will prevent things like row selection or moving control to another UI element (text field, switch, etc).

Answer 2

Make sure you have set your object to process those touch events:

[myButton addTarget:self action:@selector(buttonTouch:withEvent:) forControlEvents:UIControlEventTouchUpInside];

And then process the touch event in the method you declared:

- (IBAction) buttonTouch:(id) sender withEvent:(UIEvent *) event

Updated for UIView (Assuming you already have an outlet created and wired up):

[myView addTarget:self action:@selector(myTouchEvent:withEvent:) forControlEvents:UIControlEventTouchUpInside];

And then:

- (IBAction) myTouchEvent:(id) sender withEvent:(UIEvent *) event

Now that I understand what you are trying to do (dismiss the keyboard when touching outside the textbox), there is a simple solution that works well with almost every scenario).

Step 1 - Create a button that is sized the same as the View that the TableViewController is placed in. (large button). Step 2 - Send that button to the back (Editor->Arrange->Send to Back) Step 3 - Wire up an IBAction to that button and call it dismissKeyboardButtonPressed (hint if you are not already using the assistant editor, you should be) Step 4 - Inside the IBAction method put (assuming your TextField is called myTextField):

[myTextField resignFirstResponder];

Step 5 - Run it. Whenever you touch anywhere in the view outside of the textbox, it will dismiss the keyboard.

This is the method I use almost anytime I put a TextField on a view, and need to dismiss the KB when touching outside the TextField.

Answer 3

Try adding a tap gesture recognizer to your table view. That way you should be able to allow the normal behavior as well as capturing the tap event to do your extra stuff.

Answer 4

I've implemented similar functionality in one of my applications, I did use textFields rather than textViews, but it should still work. I used

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    [textField reresignFirstResponder];
}

Without doing any checks, if the user taps the resignFirstResponder method gets called, but if the user taps on the textView, then that triggers it to become the first responder again, resulting in no visible change. I've implemented this concept on an app with 9 textFields on a single view, and I have yet to experience problems.