xcode – 从Playground运行的模拟器中闪烁的UIView

Playground导入XCPlayground.
我正在创建一个UIView并调用XCPShowView()让它在模拟器中而不是在Playground中渲染.
我也以同样的方式呈现UIAlertView.

UIAlertView正常显示.
UIView在较大和较小的尺寸之间闪烁大约每秒5次,合理的不规则.
我已经尝试调整它以满足屏幕的界限,但没有运气.

代码如下……

// Playground - noun: a place where people can play

import UIKit
import Foundation
import XCPlayground

 XCPlayground.XCPSetExecutionShouldContinueIndefinitely(continueIndefinitely: true)

@objc class alertHandler: NSObject,UIAlertViewDelegate {

  func alertView(alertView: UIAlertView,clickedButtonAtIndex buttonIndex: Int) {
    if buttonIndex > 0 {

     // View things....
     let redRectangleFrame = CGRect(x: 0,y: 0,width: 200,height: 200)
     let redRectangle = UIView(frame: redRectangleFrame)
     redRectangle.backgroundColor = UIColor.redColor()
     redRectangle.setTranslatesAutoresizingMaskIntoConstraints(false)
     XCPShowView("Red Rectangle",redRectangle)

     // Alert view things...
     let recevingAlertView = alertView

     let text = alertView.textFieldAtIndex(0)?.text
     println("(text!)")
     println("Button (buttonIndex)")
    }
  }
}

let anAlertHandler = alertHandler()

let status = "Hey there!"
let message = "Do you have a moment to talk about our Lord and Saviour,Cthulhu?"
let cancel = "Sounds wierd"
let ok = "Oooh! Yes"

let alert = UIAlertView(title: status,message: message,delegate: anAlertHandler,cancelButtonTitle: cancel,otherButtonTitles: ok)
alert.alertViewStyle = UIAlertViewStyle.PlainTextInput
alert.show()

XCPShowView("Alert",alert)