iOS按钮标题颜色不会改变

Question

我正在使用以下代码动态创建UIButton,该代码按照指定的样式创建它.

let frame = CGRect(x: 10, y: 6, width: 60, height: 30 )    
let button = UIButton(frame: frame)
button.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)
button.backgroundColor = UIColor.whiteColor()
button.addTarget(self, action: "filterByCategory:", forControlEvents: UIControlEvents.TouchUpInside)
self.categoryScrollView.addSubview(button)

使用此按钮,我想在点击时切换样式.以下代码更改背景颜色,但不更改标题颜色.知道为什么标题颜色不会改变？

func filterByCategory(sender:UIButton) {

    if sender.backgroundColor != UIColor.blackColor() {
        sender.setTitleColor(UIColor.whiteColor(), forState: UIControlState.Selected)
        sender.backgroundColor = UIColor.blackColor()
    } else {
        sender.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)
        sender.backgroundColor = UIColor.whiteColor()
    }

}

Answer 1

因为您的按钮会UIControlState.Normal在您触摸后再返回到它.Highlighted,然后它就变成了.Normal

你应该设置 sender.setTitleColor(UIColor.whiteColor(), forState: UIControlState.Selected)

至

sender.setTitleColor(UIColor.whiteColor(), forState: UIControlState. Normal)

或者,只是为所有状态设置它,因为你检查了颜色

sender.setTitleColor(UIColor.whiteColor(), forState: [.Normal,.Selected,.Highlighted])

*编辑:上面不起作用,可以NSAttributedString改用

if self.loginButton.backgroundColor == UIColor.blackColor() {
            let tittle = NSAttributedString(string: "Login", attributes: [NSForegroundColorAttributeName: UIColor.blackColor()])
            loginButton.setAttributedTitle(tittle, forState: .Normal)
            loginButton.backgroundColor = UIColor.whiteColor()
        } else {
            let tittle = NSAttributedString(string: "Login", attributes: [NSForegroundColorAttributeName: UIColor.whiteColor()])
            loginButton.setAttributedTitle(tittle, forState: .Normal)
            loginButton.backgroundColor = UIColor.blackColor()
        }