Unwanted line on tab bar on iPhone 6

问题

Under iOS 8.1 a 1px line is showing on my tab bar. This problem is only present on iPhone 6. Here's another post with the same problem. Here is a screenshot of my tab bar.

I am using this code in Swift for my tab bar.

tabBarController?.tabBar.backgroundImage = UIImage(named: "tabbar_shadow.png")
tabBarController?.tabBar.backgroundColor = UIColor.clearColor()
tabBarController?.tabBar.shadowImage = UIImage()
tabBarController?.tabBar.translucent = true

This is working fine but a 1px line is showing up above the tab bar on iPhone 6.

来源：https://stackoverflow.com/questions/29160096/unwanted-line-on-tab-bar-on-iphone-6