UITextView IBDesignable填充

Question

如何创建IBDesignable UITextView，以便在界面构建器中调整文本的插页？我已经添加了可检查的属性topInset、bottomInset等，但是现在我很难弄清楚如何实际更新UITextView的插入，以便将更改反映在IB中

import UIKit

private let kPlaceholderTextViewInsetSpan: CGFloat = 8

@IBDesignable class UIDesignableTextView: UITextView {
    // variables

    @IBInspectable var topInset: CGFloat = 0.0
    @IBInspectable var leftInset: CGFloat = 0.0
    @IBInspectable var bottomInset: CGFloat = 0.0
    @IBInspectable var rightInset: CGFloat = 0.0

    var insets: UIEdgeInsets {
        get {
            return UIEdgeInsetsMake(topInset, leftInset, bottomInset, rightInset)
        }
        set {
            topInset = newValue.top
            leftInset = newValue.left
            bottomInset = newValue.bottom
            rightInset = newValue.right
        }
    }

    @IBInspectable var placeholder: NSString? { didSet { setNeedsDisplay() } }
    @IBInspectable var placeholderColor: UIColor = UIColor.lightGray

    override var text: String! { didSet { setNeedsDisplay() } }

    override var attributedText: NSAttributedString! { didSet { setNeedsDisplay() } }

    override var contentInset: UIEdgeInsets { didSet { setNeedsDisplay() } }

    override var font: UIFont? { didSet { setNeedsDisplay() } }

    override var textAlignment: NSTextAlignment { didSet { setNeedsDisplay() } }

    // MARK: - Lifecycle

    /** Override coder init, for IB/XIB compatibility */
    #if !TARGET_INTERFACE_BUILDER
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        listenForTextChangedNotifications()
    }

    /** Override common init, for manual allocation */
    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        listenForTextChangedNotifications()
    }
    #endif

    /** Initializes the placeholder text view, waiting for a notification of text changed */
    func listenForTextChangedNotifications() {
        NotificationCenter.default.addObserver(self, selector: #selector(UIDesignableTextView.textChangedForPlaceholderTextView(_:)), name:NSNotification.Name.UITextViewTextDidChange , object: self)
        NotificationCenter.default.addObserver(self, selector: #selector(UIDesignableTextView.textChangedForPlaceholderTextView(_:)), name:NSNotification.Name.UITextViewTextDidBeginEditing , object: self)
    }

    /** willMoveToWindow will get called with a nil argument when the window is about to dissapear */
    override func willMove(toWindow newWindow: UIWindow?) {
        super.willMove(toWindow: newWindow)
        if newWindow == nil { NotificationCenter.default.removeObserver(self) }
        else { listenForTextChangedNotifications() }
    }

            func textChangedForPlaceholderTextView(_ notification: Notification) {
        setNeedsDisplay()
        setNeedsLayout()
    }

    override func draw(_ rect: CGRect) {
        super.draw(rect)

        if text.characters.count == 0 && self.placeholder != nil {
            let baseRect = placeholderBoundsContainedIn(self.bounds)
            let font = self.font ?? self.typingAttributes[NSFontAttributeName] as? UIFont ?? UIFont.systemFont(ofSize: UIFont.systemFontSize)

            self.placeholderColor.set()

            var customParagraphStyle: NSMutableParagraphStyle!
            if let defaultParagraphStyle =  typingAttributes[NSParagraphStyleAttributeName] as? NSParagraphStyle {
                customParagraphStyle = defaultParagraphStyle.mutableCopy() as! NSMutableParagraphStyle
            } else { customParagraphStyle = NSMutableParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle }
            // set attributes
            customParagraphStyle.lineBreakMode = NSLineBreakMode.byTruncatingTail
            customParagraphStyle.alignment = self.textAlignment
            let attributes = [NSFontAttributeName: font, NSParagraphStyleAttributeName: customParagraphStyle.copy() as! NSParagraphStyle, NSForegroundColorAttributeName: self.placeholderColor]
            // draw in rect.
            self.placeholder?.draw(in: baseRect, withAttributes: attributes)
        }
    }

    func placeholderBoundsContainedIn(_ containerBounds: CGRect) -> CGRect {
        // get the base rect with content insets.
        let baseRect = UIEdgeInsetsInsetRect(containerBounds, UIEdgeInsetsMake(kPlaceholderTextViewInsetSpan, kPlaceholderTextViewInsetSpan/2.0, 0, 0))

        // adjust typing and selection attributes
        if let paragraphStyle = typingAttributes[NSParagraphStyleAttributeName] as? NSParagraphStyle {
            baseRect.offsetBy(dx: paragraphStyle.headIndent, dy: paragraphStyle.firstLineHeadIndent)
        }

        return baseRect
    }

Answer 1

这就是你所需要做的：

import UIKit

@IBDesignable class TextViewWithInsets: UITextView {

    @IBInspectable var topInset: CGFloat = 0 {
        didSet {
            self.contentInset = UIEdgeInsetsMake(topInset, self.contentInset.left, self.contentInset.bottom, self.contentInset.right)
        }
    }

    @IBInspectable var bottmInset: CGFloat = 0 {
        didSet {
            self.contentInset = UIEdgeInsetsMake(self.contentInset.top, self.contentInset.left, bottmInset, self.contentInset.right)
        }
    }

    @IBInspectable var leftInset: CGFloat = 0 {
        didSet {
            self.contentInset = UIEdgeInsetsMake(self.contentInset.top, leftInset, self.contentInset.bottom, self.contentInset.right)
        }
    }

    @IBInspectable var rightInset: CGFloat = 0 {
        didSet {
            self.contentInset = UIEdgeInsetsMake(self.contentInset.top, self.contentInset.left, self.contentInset.bottom, rightInset)
        }
    }
}

如您所见，这些是我创建的UITextView的TextViewWithInsets子类的属性。您需要重写属性方法的didSet部分。然后，在Interface Builder中，这四个属性(Top Inset、Bottom Inset、Left Inset和Right Inset)将出现在属性检查器中：attributes inspector in IB for new class

只需确保在身份检查器中将情节提要中的TextView对象设置为TextViewWithInsets或您选择的命名方式：Set class of Text View object in storyboard to custom class

Answer 2

Swift 5

如果您想在项目中的所有UITextViews中使用它，请使用以下内容：

import UIKit
@IBDesignable extension UITextView {

    @IBInspectable var topPadding: CGFloat {
        get {
            return contentInset.top
        }
        set {
            self.contentInset = UIEdgeInsets(top: newValue,
                                             left: self.contentInset.left,
                                             bottom: self.contentInset.bottom,
                                             right: self.contentInset.right)
        }
    }

    @IBInspectable var bottomPadding: CGFloat {
        get {
            return contentInset.bottom
        }
        set {
            self.contentInset = UIEdgeInsets(top: self.contentInset.top,
                                             left: self.contentInset.left,
                                             bottom: newValue,
                                             right: self.contentInset.right)
        }
    }

    @IBInspectable var leftPadding: CGFloat {
        get {
            return contentInset.left
        }
        set {
            self.contentInset = UIEdgeInsets(top: self.contentInset.top,
                                             left: newValue,
                                             bottom: self.contentInset.bottom,
                                             right: self.contentInset.right)
        }
    }

    @IBInspectable var rightPadding: CGFloat {
        get {
            return contentInset.right
        }
        set {
            self.contentInset = UIEdgeInsets(top: self.contentInset.top,
                                             left: self.contentInset.left,
                                             bottom: self.contentInset.bottom,
                                             right: newValue)
        }
    }
}