UITextView IBDesignable填充

Question

如何創建一個IBDesignable UITextView，以便我可以調整界面構建器中文本的內插值？我已經添加了檢查屬性topInset，bottomInset等，但現在我無法弄清楚如何實際更新UITextView這樣的插圖，這些變化反映在IB

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

這是你所需要的要做到：

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) 
     } 
    } 
} 

正如你所看到的，這些都是UITextView的TextViewWithInsets子我創建的性質。您需要覆蓋屬性方法的didSet部分。然後，在界面構建器中，這四個屬性（頂部插入，底部插入，左側插入和右側插入）將出現在屬性檢查器中：attributes inspector in IB for new class

只要確保在Identity Inspector中設置了故事板中的TextView對象爲TextViewWithInsets或任何你選擇這樣命名的：Set class of Text View object in storyboard to custom class