在 iOS 8 上自定义 UISegmentedControl

iOS 7 和 8 似乎使自定义 UISegmentedControl 的旧方法不再完全起作用。我一直像过去一样设置分隔线图像和所有内容，但似乎有一些以前的 iOS 版本中不存在的新状态，因此出现了一些奇怪的视觉效果。

这是我正在使用的代码

// Set divider images
    self.setDividerImage(UIImage(named: "SegmentedControlNoneSelected"), forLeftSegmentState: .Normal, rightSegmentState: .Normal, barMetrics: .Default)
    self.setDividerImage(UIImage(named: "SegmentedControlRightSelected"), forLeftSegmentState: .Normal, rightSegmentState: .Selected, barMetrics: .Default)
    self.setDividerImage(UIImage(named: "SegmentedControlRightSelected"), forLeftSegmentState: .Normal, rightSegmentState: .Highlighted, barMetrics: .Default)
    self.setDividerImage(UIImage(named: "SegmentedControlLeftSelected"), forLeftSegmentState: .Selected, rightSegmentState: .Normal, barMetrics: .Default)
    self.setDividerImage(UIImage(named: "SegmentedControlBothSelected"), forLeftSegmentState: .Selected, rightSegmentState: .Highlighted, barMetrics: .Default)
    self.setDividerImage(UIImage(named: "SegmentedControlBothSelected"), forLeftSegmentState: .Selected, rightSegmentState: .Selected, barMetrics: .Default)
    self.setDividerImage(UIImage(named: "SegmentedControlBothSelected"), forLeftSegmentState: .Highlighted, rightSegmentState: .Selected, barMetrics: .Default)
    self.setDividerImage(UIImage(named: "SegmentedControlBothSelected"), forLeftSegmentState: .Highlighted, rightSegmentState: .Highlighted, barMetrics: .Default)
    self.setDividerImage(UIImage(named: "SegmentedControlLeftSelected"), forLeftSegmentState: .Highlighted, rightSegmentState: .Normal, barMetrics: .Default)


    // Set background images
    var normalBackgroundImage = UIImage(named: "SegmentedControlNormal")
    self.setBackgroundImage(normalBackgroundImage, forState: .Normal, barMetrics: .Default)

    var selectedBackgroundImage = UIImage(named: "SegmentedControlSelected");
    self.setBackgroundImage(selectedBackgroundImage, forState: .Selected, barMetrics: .Default)
    self.setBackgroundImage(selectedBackgroundImage, forState: .Highlighted, barMetrics: .Default)
    self.setBackgroundImage(selectedBackgroundImage, forState: .Disabled, barMetrics: .Default)
    self.setBackgroundImage(selectedBackgroundImage, forState: .Application, barMetrics: .Default)
    self.setBackgroundImage(selectedBackgroundImage, forState: .Reserved, barMetrics: .Default)

有一些现在应该处理的新状态：

//The highlighted button can be still unselected
[self.mySegmentedControl setBackgroundImage:unselectedBackgroundImage
                                   forState:UIControlStateHighlighted
                                 barMetrics:UIBarMetricsDefault];

//The alredy selected button is stil selected when it is highlighted
[self.mySegmentedControl setBackgroundImage:selectedBackgroundImage
                                   forState:UIControlStateHighlighted|UIControlStateSelected
                                 barMetrics:UIBarMetricsDefault];


//Handle when the right segment is highlighted but the left is selected
[self.mySegmentedControl setDividerImage:leftSelectedImage
                       forLeftSegmentState:UIControlStateSelected
                       rightSegmentState:UIControlStateHighlighted
                              barMetrics:UIBarMetricsDefault];

//Handle when the right segment is already selected and just highlighted and the right is normal
[self.mySegmentedControl setDividerImage:leftSelectedImage
                     forLeftSegmentState:UIControlStateHighlighted|UIControlStateSelected
                       rightSegmentState:UIControlStateNormal
                              barMetrics:UIBarMetricsDefault];

//Handle when the left segment is highlighted but the right is selected    
[self.mySegmentedControl setDividerImage:rightSelectedImage
                     forLeftSegmentState:UIControlStateHighlighted
                       rightSegmentState:UIControlStateSelected
                              barMetrics:UIBarMetricsDefault];

//Handle when the left segment is already selected and just highlighted and the left is normal
[self.mySegmentedControl setDividerImage:rightSelectedImage
                     forLeftSegmentState:UIControlStateNormal
                       rightSegmentState:UIControlStateHighlighted|UIControlStateSelected
                              barMetrics:UIBarMetricsDefault];

看起来，分隔线图像宽度现在很重要。它对内容标签的宽度和位置有影响。因此分隔线图像应尽可能缩小。