Swift-UITextView占位文字及占位文字颜色扩展(可在xib中直接使用)

使用案例

extension UITextView {private struct RuntimeKey {static let hw_placeholderLabelKey = UnsafeRawPointer.init(bitPattern: "hw_placeholderLabelKey".hashValue)/// ...其他Key声明}/// 占位文字@IBInspectable public var placeholder: String {get {return self.placeholderLabel.text ?? ""}set {self.placeholderLabel.text = newValue}}/// 占位文字颜色@IBInspectable public var placeholderColor: UIColor {get {return self.placeholderLabel.textColor}set {self.placeholderLabel.textColor = newValue}}private var placeholderLabel: UILabel {get {var label = objc_getAssociatedObject(self, UITextView.RuntimeKey.hw_placeholderLabelKey!) as? UILabelif label == nil {if (self.font == nil) {self.font = UIFont.systemFont(ofSize: 14)}label = UILabel.init(frame: self.bounds)label?.numberOfLines = 0label?.font = self.fontlabel?.textColor = UIColor.lightGrayself.addSubview(label!)self.setValue(label!, forKey: "_placeholderLabel")objc_setAssociatedObject(self, UITextView.RuntimeKey.hw_placeholderLabelKey!, label!, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)self.sendSubview(toBack: label!)}return label!}set {objc_setAssociatedObject(self, UITextView.RuntimeKey.hw_placeholderLabelKey!, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)}}
}