Swift inputAccessoryView override bug

问题:

I'm experiencing a weird bug with the appearance of my inputAccessoryView. While in the middle of a transition, it appears like so:

After the transition, it appears as it should:

I override the property like so:

    override var inputAccessoryView: UIView! {
    get {
        if composeView == nil {
            composeView = CommentComposeView(frame: CGRectMake(0, 0, 0, MinimumToolbarHeight - 0.5))
            self.setupSignals()
        }

        return composeView
    }
}

I'm wondering if anyone can point out any obvious flaw in what I'm doing or provide some more information on how to ensure my view appears as it should, before, during, and after transitions.

Thanks!

EDIT

Here's my CommentComposeView:

import UIKit

class CommentComposeView: UIToolbar {
    var textView: SAMTextView!
    var sendButton: UIButton!

    private var didSetConstraints: Bool = false

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.initialize()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.initialize()
    }

    private func initialize() {
        textView = SAMTextView(frame: CGRectZero)
        sendButton = UIButton.buttonWithType(.System) as UIButton

        self.barStyle = .Black
        self.translucent = true

        textView.backgroundColor = UIColor.presentOffWhite()
        textView.font = UIFont.presentLightMedium()
        textView.layer.borderWidth = 0.5
        textView.layer.cornerRadius = 5
        textView.placeholder = "Comment"
        textView.scrollsToTop = false
        textView.textContainerInset = UIEdgeInsetsMake(4, 3, 3, 3)
        textView.keyboardAppearance = .Dark
        textView.keyboardType = .Twitter
        self.addSubview(textView)

        sendButton = UIButton.buttonWithType(.System) as UIButton
        sendButton.enabled = false
        sendButton.titleLabel!.font = UIFont.presentBoldLarge()
        sendButton.setTitle("Send", forState: .Normal)
        sendButton.setTitleColor(UIColor.whiteColor(), forState: .Normal)
        sendButton.setTitleColor(UIColor.presentCyan(), forState: .Highlighted)
        sendButton.setTitleColor(UIColor.presentLightGray(), forState: .Disabled)
        sendButton.contentEdgeInsets = UIEdgeInsetsMake(6, 6, 6, 6)
        self.addSubview(sendButton)

        RAC(self.sendButton, "enabled") <~ self.textView.rac_textSignal()
            .map { text in
                return (text as NSString).length > 0
        }

        textView.setTranslatesAutoresizingMaskIntoConstraints(false)
        sendButton.setTranslatesAutoresizingMaskIntoConstraints(false)
    }

    override func updateConstraints() {
        super.updateConstraints()

        if !didSetConstraints {
            // TODO: Replace raw constraints with a friendlier looking DSL
            self.addConstraint(
                NSLayoutConstraint(item: textView, attribute: .Left, relatedBy: .Equal, toItem: self, attribute: .Left, multiplier: 1, constant: 8)
            )

            self.addConstraint(
                NSLayoutConstraint(item: textView, attribute: .Top, relatedBy: .Equal, toItem: self, attribute: .Top, multiplier: 1, constant: 7.5)
            )

            self.addConstraint(
                NSLayoutConstraint(item: textView, attribute: .Right, relatedBy: .Equal, toItem: sendButton, attribute: .Left, multiplier: 1, constant: -2)
            )

            self.addConstraint(
                NSLayoutConstraint(item: textView, attribute: .Bottom, relatedBy: .Equal, toItem: self, attribute: .Bottom, multiplier: 1, constant: -8)
            )

            self.addConstraint(
                NSLayoutConstraint(item: sendButton, attribute: .Right, relatedBy: .Equal, toItem: self, attribute: .Right, multiplier: 1, constant: 0)
            )

            self.addConstraint(
                NSLayoutConstraint(item: sendButton, attribute: .Bottom, relatedBy: .Equal, toItem: self, attribute: .Bottom, multiplier: 1, constant: -4.5)
            )
        }
    }
}

回答1:

This is iOS8 issue with inputAccessoryView autolayout. Issue is that UIToolbar's subview of clas _UIToolbarBackground is not positioned properly during initial layout. Try to do next things:

1. Make CommentComposeView subclassing UIView, not UIToolbar, add instance of UIToolbar as subview.
2. Use autolayout masks (not actual constraints) inside your CommentComposeView
3. Override -layoutSubviews in your CommentComposeView like this:

- (void)layoutSubviews
{
    [super layoutSubviews];

    contentToolbar.frame = self.bounds;
    sendButton.frame = CGRectMake(0.f, 0.f, 44.f, self.bounds.size.height);
    textView.frame = CGRectMake(44.f, 0.f, self.bounds.size.width - 44.f, self.bounds.size.height);
}