UITextField有placeholder属性很方便，UITextView没有，我们可以继承重写drawRect方法,不啰嗦 直接上代码,字体大小可以自己定义看需要吧（欢迎指出不当之处）
import UIKit
class HZTextView: UITextView {
/// 占位文字
var placeholder: String?
/// 占位文字颜色
var placeholderColor: UIColor? = UIColor.lightGray
override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
// 设置默认字体
self.font = UIFont.systemFont(ofSize: 15)
// 使用通知监听文字改变
NotificationCenter.default.addObserver(self, selector: #selector(textDidChange(_:)), name: UITextView.textDidChangeNotification, object: nil)
}
deinit {
NotificationCenter.default.removeObserver(self)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func draw(_ rect: CGRect) {
// 如果有文字,就直接返回,不需要画占位文字
if self.hasText {
return
}
// 属性
let attrs: [NSAttributedString.Key : Any] = [NSAttributedString.Key.foregroundColor: self.placeholderColor as Any, NSAttributedString.Key.font: self.font!]
// 文字
var rect1 = rect
rect1.origin.x = 5
rect1.origin.y = 8
rect1.size.width = rect1.size.width - 2*rect1.origin.x
(self.placeholder! as NSString).draw(in: rect1, withAttributes: attrs)
}
@objc func textDidChange(_ note: Notification) {
// 会重新调用drawRect:方法
self.setNeedsDisplay()
}
