Add subviews on Customize UIView works not as expect - ios

Question

I subclass a class of UIView called:AURTabView. Then I drag 3 views(white background) to storyboard to auto layout them with 1/3 screen width of each. Then i add a UIButton on the init method, it works well so far as below:
Then i want to add another two UIViews on to them. The weird thing is the first and third AUTRabView works as expect, but the middle one doesn't.
This is really weird. I checked UIView hierarchy like below:
Any point?
Here is the code:
class AURTabView: UIView {
let tabButton = UIButton()
let smallCircle = UIView()
let largeCircle = UIView()
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.addSubview(tabButton)
self.addSubview(smallCircle)
self.addSubview(largeCircle)
}
override func layoutSubviews() {
super.layoutSubviews()
let height = self.frame.height
tabButton.frame = CGRect(x: (self.frame.width-height)/2, y: 0, width: height, height: height)
tabButton.backgroundColor = UIColor.greenColor()
smallCircle.frame = CGRect(x: CGRectGetMidX(self.frame)-2.5, y: height-10-8, width: 5, height: 5)
smallCircle.backgroundColor = UIColor.redColor()
largeCircle.frame = CGRect(x: CGRectGetMidX(self.frame)-5, y: height-8, width: 10, height: 10)
largeCircle.backgroundColor = UIColor.redColor()
print(smallCircle)
print(largeCircle)
}
override func drawRect(rect: CGRect) {
tabButton.layer.cornerRadius = tabButton.frame.width/2
}
}

Answer 1

Use this
import UIKit
class AURTabView: UIView {
let tabButton = UIButton()
let smallCircle = UIView()
let largeCircle = UIView()
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.addSubview(tabButton)
self.addSubview(smallCircle)
self.addSubview(largeCircle)
}
override func layoutSubviews() {
super.layoutSubviews()
let height = self.frame.height
tabButton.frame = CGRect(x: (self.frame.width-height)/2, y: 0, width: height, height: height)
tabButton.backgroundColor = UIColor.greenColor()
smallCircle.frame = CGRect(x: self.frame.width/2 - 2.5, y: height-10-8, width: 5, height: 5)
smallCircle.backgroundColor = UIColor.blackColor()
largeCircle.frame = CGRect(x: self.frame.width/2 - 5, y: height-8, width: 10, height: 10)
largeCircle.backgroundColor = UIColor.redColor()
print(smallCircle)
print(largeCircle)
}
override func drawRect(rect: CGRect) {
tabButton.layer.cornerRadius = tabButton.frame.width/2
}
}