我有两个具有相同逻辑的 View Controller (A 和 B):
class A: UIViewController {
override func viewDidAppear(_ animated: Bool) {
self.contrast(first: nil, second: self.numberOne)
timer = Timer.scheduledTimer(timeInterval: 0.7, target: self, selector: #selector(update), userInfo: nil, repeats: true)
}
@objc private func update() {
if count == 0 {
self.contrast(first: self.numberOne, second: self.numberTwo)
} else if count == 1 {
self.contrast(first: self.numberTwo, second: self.numberThree)
} else if count == 2 {
self.contrast(first: self.numberThree, second: self.numberFour)
} else if count == 3 {
self.contrast(first: self.numberFour, second: nil)
self.timer.invalidate()
}
self.count += 1
}
}
class B: UIViewController {
override func viewDidAppear(_ animated: Bool) {
self.contrast(first: nil, second: self.numberOne)
timer = Timer.scheduledTimer(timeInterval: 0.7, target: self, selector: #selector(update), userInfo: nil, repeats: true)
}
@objc private func update() {
if count == 0 {
self.contrast(first: self.numberOne, second: self.numberTwo)
} else if count == 1 {
self.contrast(first: self.numberTwo, second: self.numberThree)
} else if count == 2 {
self.contrast(first: self.numberThree, second: self.numberFour)
} else if count == 3 {
self.contrast(first: self.numberFour, second: nil)
self.timer.invalidate()
}
self.count += 1
}
}
如您所见,它们都使用完全相同的代码。我试图使用 UIViewController 的扩展来解决它,但事情变得有点困惑。然后我听说了委托(delegate)模式,但我找不到任何与此场景相关的示例!
编辑:viewDidAppear 方法也完全相同。如果我能以某种方式从父类(super class)中覆盖它?
最佳答案
实际上,有几种方法可以避免重复代码。问题是您应该了解这些类的逻辑以及它们之间的相互关系,以决定如何实现它们。
首先,这两个类是完全一样的。这些类中是否有其他不同的代码?如果不是,则不需要 2 个相同的类(class),只需留下 1 个类(class)即可。
如果是,则取决于每个类实现的其他代码。例如,如果您的 B 类应该与 A 类完全相同并且继承了它的所有特性并且还添加了一些新特性,那么看起来 B 类是 A 类的子类。
classA: UIViewController {
override func viewDidAppear(_ animated: Bool) {
self.contrast(first: nil, second: self.numberOne)
timer = Timer.scheduledTimer(timeInterval: 0.7, target: self, selector: #selector(update), userInfo: nil, repeats: true)
}
@objc private func update() {
if count == 0 {
self.contrast(first: self.numberOne, second: self.numberTwo)
} else if count == 1 {
self.contrast(first: self.numberTwo, second: self.numberThree)
} else if count == 2 {
self.contrast(first: self.numberThree, second: self.numberFour)
} else if count == 3 {
self.contrast(first: self.numberFour, second: nil)
self.timer.invalidate()
}
self.count += 1
}
}
classB: classA {
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
addNewFeatures()
}
func addNewfeatures {
//some additional code
}
}
如果两个类不同并且彼此不相关(如父子类),您可以改变某些协议(protocol)中的常见行为,通过扩展将默认实现添加到该协议(protocol)并指示您的类将实现该协议(protocol)。
protocol Contrasting {
func contrast(first:Int, second: Int)
}
extension Contrasting {
func contrast(first: Int, second: Int) {
//make contrast
}
}
classA: UIViewController, Contrasting {
override func viewDidAppear(_ animated: Bool) {
contrast(first: nil, second: self.numberOne)
}
}
classB: UIViewController, Contrasting {
override func viewDidAppear(_ animated: Bool) {
contrast(first: nil, second: self.numberOne)
}
}
https://krakendev.io/blog/subclassing-can-suck-and-heres-why阅读本教程以了解何时使用继承和协议(protocol)。
请在处理数字时使用 switch 以避免大量 else if 语句。
switch count {
case 0:
self.contrast(first: self.numberOne, second: self.numberTwo)
case 1:
self.contrast(first: self.numberTwo, second: self.numberThree)
case 2:
self.contrast(first: self.numberThree, second: self.numberFour)
case 3:
self.contrast(first: self.numberFour, second: nil)
default:
break
}
关于ios - 如何避免使用子类化和/或委托(delegate)模式(Swift)为两个 View Controller 编写相同的函数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/44467933/