How do you set canBecomeFocused for a custom view

问题:

I am making an application for tvOS. I have a view that contains a UIButton and a custom UIView that contains a couple other custom views. The simulator is only able to highlight the UIButton and not the custom view.

According to the Building Apple TV Apps Docs:

If your custom view needs to be focusable, override canBecomeFocused to return YES (by default, it returns NO).

According to the canBecomeFocused Docs:

canBecomeFocused will return

YES if the view can become focused; NO otherwise.

However, attempting to assign YES to canBecomeFocused by doing this:

self.customView.canBecomeFocused = YES;

Gives this error:

No setter method 'setCanBecomeFocused:' for assignment to property

How do I accomplish this?

回答1:

It looks like UIView declares the function/property.

Have you tried overriding the function like so?

Swift

override func canBecomeFocused() -> Bool {
    return true
}

Objective-C

- (BOOL)canBecomeFocused {
    return YES;
}

I haven't tried this, but it may work for you.

回答2:

Besides of overriding the canBecomeFocused method in your custom view:

override func canBecomeFocused() -> Bool {
    return true
}

Make sure your custom view userInteractionEnabled is true. This is the complete list to be sure your view can be focused:

Why Is This View Not Focusable?

There are a number of reasons a view that is expected to be focusable may not be, including (but not limited to):

• The view’s canBecomeFocused method returns NO.
• The view’s hidden property has a value of YES.
• The view’s alpha property has a value of 0.
• The view’s user interaction is disabled.
• The view is obscured by another view on top of it.

回答3:

Above answers are not enough this my customView code block.

Swift

import UIKit

class Focus: UIView {

    /*
    // Only override drawRect: if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func drawRect(rect: CGRect) {
        // Drawing code
    }
    */

    override func canBecomeFocused() -> Bool {
        return true
    }

    override func didUpdateFocusInContext(context: UIFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {
        if context.previouslyFocusedView === self {
            UIView.animateWithDuration(0.1, animations: { () -> Void in
                context.previouslyFocusedView?.transform = CGAffineTransformMakeScale(1.0, 1.0)
            })
        }

        if context.nextFocusedView === self {
            UIView.animateWithDuration(0.1, animations: { () -> Void in
                context.nextFocusedView?.transform = CGAffineTransformMakeScale(1.4, 1.4)
            })
        }
    }
}