ios - 自定义 iOS 键盘 – 按键太慢

Question

我正在使用自定义 iOS 键盘，但似乎无法加快按键响应速度。我遇到的问题是按键对 touchUpInside 事件的响应有一个小但显着的延迟。标准 iOS 键盘(以及我下载的大多数自定义键盘)会立即响应。我遇到的短暂延迟会导致严重的可用性问题。延迟在模拟器中几乎察觉不到，但在设备 (iPhone) 上，它会导致您在快速打字时遗漏按键。

我尝试了多种技术来解决速度问题:

• 我已经使用约束构建了一次键盘，然后放弃它以支持这种基于框架的布局(我根据这个 writeup 做出了选择
• 将“优化级别”的编译器设置更改为“最快/最小”(在调试和发布时)
• 使这个类成为“final”类(如您在下面的代码中所见)。我真的没想到这会解决任何问题，但我越来越绝望了。

如何加快键盘的按键速度？键盘的大部分代码如下(我只包含了 QWERTY 键盘的功能，但数字键盘和符号键盘也有类似的功能)

为了创建项目，我只是创建了一个新的 iOS 项目，为键盘添加了一个扩展，并编写了下面的类:

    import UIKit

    final class KeyboardViewController: UIInputViewController {

var screenWidth : CGFloat = CGFloat()
var capsLockOn : Bool = false

override func viewDidLoad() {
    super.viewDidLoad()

    // Perform custom UI setup here
    view.backgroundColor = UIColor(red: 209 / 255, green: 213 / 255, blue: 219 / 255, alpha: 1)

    showQWERTYKeyboard()
}

func showQWERTYKeyboard() {

    //Setup some constants and variables that will be used for layout
    var buttonWidth : CGFloat = 26
    let buttonHeight : CGFloat = 40
    let standardButtonWidth : CGFloat = buttonWidth
    let horizontalSpaceBetweenButtons : CGFloat = 6.0
    let verticalSpaceBetweenButtons : CGFloat = 18

    var nextY : CGFloat = 0 //Tracks the current vertical position so we know where to place the next button
    var nextX : CGFloat = 1.5 //Tracks the current horizontal position so we know where to place the next button
    let standardNextX : CGFloat = nextX //Placeholder for the "nextX" value for the left-most key
    var buttonStrings : [String] = [""] //Holds the row of keys that get put on the screen

    //This outer loop iterates over each of the 4 rows. The inner loop below iterates over each letter in the array.
    var rowCounter : Int = Int()
    for rowCounter = 0; rowCounter<4; rowCounter++ {

        switch rowCounter {
        case 0:
            if capsLockOn {
                buttonStrings = ["Q", "W", "E", "R", "T", "Y", "U", "I", "O", "P"]
            }
            else {
                buttonStrings = ["q", "w", "e", "r", "t", "y", "u", "i", "o", "p"]
            }
            nextY = 4
            nextX = standardNextX
        case 1:
            if capsLockOn {
                buttonStrings = ["A", "S", "D", "F", "G", "H", "J", "K", "L"]
            }
            else {
                buttonStrings = ["a", "s", "d", "f", "g", "h", "j", "k", "l"]
            }
            nextY = (CGFloat(rowCounter) * buttonHeight) + CGFloat((rowCounter))*verticalSpaceBetweenButtons
            nextX = (((buttonWidth + horizontalSpaceBetweenButtons) * 1) + (2*4))/2
        case 2:
            if capsLockOn {
                buttonStrings = ["^^", "Z", "X", "C", "V", "B", "N", "M", "<<"]
            }
            else {
                buttonStrings = ["^^", "z", "x", "c", "v", "b", "n", "m", "<<"]
            }
            nextY = (CGFloat(rowCounter) * buttonHeight) + CGFloat((rowCounter))*verticalSpaceBetweenButtons
            nextX = standardNextX
        case 3:
            buttonStrings = ["8", "kb", "sp", "rt"]
            nextY = (CGFloat(rowCounter) * buttonHeight) + CGFloat((rowCounter))*verticalSpaceBetweenButtons
            nextX = standardNextX
        default:
            break
        }

        //This inner loop iterates the current buttonStrings array and adds a target to the buttons, styles the buttons and adds the buttons to the view
        for buttonString in buttonStrings {
            //Create a new button
            let button : UIButton = UIButton(type: UIButtonType.Custom)

            styleAButton(button, buttonTitle: buttonString) //Customize the look and feel of the button

            switch buttonString {
            case "sp":
                button.addTarget(self, action: "touchUpInsideSpace:", forControlEvents: UIControlEvents.TouchUpInside)
                buttonWidth = (standardButtonWidth + horizontalSpaceBetweenButtons) * 5
            case "kb", "KB":
                button.addTarget(self, action: "advanceToNextInputMode", forControlEvents: UIControlEvents.TouchUpInside)
                buttonWidth = standardButtonWidth * 1.33
            case "rt":
                button.addTarget(self, action: "touchUpInsideReturn:", forControlEvents: UIControlEvents.TouchUpInside)
                buttonWidth = standardButtonWidth * 2.55
            case "^^":
                button.addTarget(self, action: "touchUpInsideCapsLock:", forControlEvents: UIControlEvents.TouchUpInside)
                buttonWidth = standardButtonWidth * 1.33
            case "<<":
                button.addTarget(self, action: "touchUpInsideBackspace:", forControlEvents: UIControlEvents.TouchUpInside)
                buttonWidth = standardButtonWidth * 1.33
                nextX = nextX + 7
            case "8":
                button.addTarget(self, action: "touchUpInsideNumbers:", forControlEvents: UIControlEvents.TouchUpInside)
                buttonWidth = standardButtonWidth * 1.33
            case "z", "Z": //Special case to simplify layout of the caps lock button
                button.addTarget(self, action: "touchUpInsideLetter:", forControlEvents: UIControlEvents.TouchUpInside)
                buttonWidth = standardButtonWidth
                nextX = nextX + 7
            default:
                button.addTarget(self, action: "touchUpInsideLetter:", forControlEvents: UIControlEvents.TouchUpInside)
                buttonWidth = standardButtonWidth
            }

            //Make the button
            button.frame = CGRectMake(nextX, nextY, buttonWidth, buttonHeight)

            //Determine horizontal placement for the next key
            nextX = nextX + horizontalSpaceBetweenButtons + buttonWidth

            //Add button to the view
            self.view.addSubview(button)
        }
    }
}
    func styleAButton(button : UIButton, buttonTitle : String) {



    //Configure button look and feel
    button.backgroundColor = UIColor.whiteColor()
    button.setTitle(buttonTitle, forState: UIControlState.Normal)
    button.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)
    button.titleLabel?.font = UIFont.systemFontOfSize(23.0)

    button.layer.cornerRadius = 4.0
    button.layer.masksToBounds = true
    button.layer.shadowColor = UIColor.lightGrayColor().CGColor
    button.layer.shadowOpacity = 0.8
    button.layer.shadowRadius = 6.0
    button.layer.shadowOffset = CGSizeMake(1.0, 1.0)
    button.contentEdgeInsets = UIEdgeInsetsMake(-3, -3, -3, -3)

}

//Shows the QWERTY keyboard
func touchUpInsideLetters(sender : UIButton) {
    for someView in view.subviews {
        someView.removeFromSuperview()
    }
    showQWERTYKeyboard()
}

//Shows the "numbers" keyboard
func touchUpInsideNumbers(sender : UIButton) {
    for someView in view.subviews {
        someView.removeFromSuperview()
    }
    showNumericKeyboard()
}

//Shows the keyboard with characters like [ ] { } etc.
func touchUpInsideMoreSymbols(sender : UIButton) {
    for someView in view.subviews {
        someView.removeFromSuperview()
    }
    showMoreSymbolsKeyboard()
}

//inserts the character of the key being pressed
func touchUpInsideLetter(sender : UIButton) {
    self.textDocumentProxy.insertText((sender.titleLabel?.text)!)

}

//inserts a space character
func touchUpInsideSpace(sender : UIButton) {
    let textToInsert : String = " "
    self.textDocumentProxy.insertText(textToInsert)

}

//inserts a new line character
func touchUpInsideReturn(sender : UIButton) {
    let textToInsert : String = "\n"
    self.textDocumentProxy.insertText(textToInsert)

}

//Toggles the global capsLockOn variable to be true or false (depending on current state).
func touchUpInsideCapsLock(sender : UIButton) {
    capsLockOn = !capsLockOn
    showQWERTYKeyboard()

}

//Inserts a backspace
func touchUpInsideBackspace(sender : UIButton) {
    (textDocumentProxy as UIKeyInput).deleteBackward()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated
}
    } //End of class

感谢您提供的任何帮助。我是 iOS 开发的新手，我希望我只是遗漏了一些明显的东西。

Answer 1

我刚刚知道了!令人惊讶的是，除非您配置 shadowPath 属性，否则绘制阴影的开销非常大。我没有在我的“styleAButton”方法中这样做，所以我这样添加它:

    button.layer.shadowPath = UIBezierPath(rect: button.bounds).CGPath

有关更多详细信息，请参阅 post由某人讨论幕后发生的事情。

我猜测问题可能与按钮的样式有关，因此能够隔离问题。当时这对我来说没有多大意义，但现在我明白了，因为按钮在按键时是动画的，所以它在那个阴影上做了一些绘制，因为这是一个昂贵的操作，它减慢了插入角色(它可能阻塞了主线程)。