[英]Adressing instance created inside closure in init
我有一個ControlPanel
類,需要在初始化期間對其UI元素進行一些調整。 我想將這些調整作為init()
的閉包進行傳遞。 但是我該如何正確地引用self
呢? 這樣做時...
let cornerRadius = ControlPanel(title: "Corner Radius",
layout: .oneSlider,
sliderRange: (0.0, 30.0),
setup: { self.someProperty = 5 }
)
...迅捷當然假設self
是指我在其中調用此初始化程序的類。 這完全無關。 是否有類似theSelfWhenThisClosureIsBeingExecuted
語法?
我的ControlPanel
初始化定義如下:
init(title: String, layout: PanelControlLayoutType, sliderRange: (min: Float, max: Float), editClosure1of1: ((Float) -> ())?, setup: () -> ()) {
super.init(frame: CGRect())
commonInit(title: title)
guard layout == .oneSlider else { fatalError("Wrong paneltype") }
let singleSlider = UISlider()
slider1?[0] = singleSlider
singleSlider.minimumValue = sliderRange.min
singleSlider.maximumValue = sliderRange.max
self.addSubview(singleSlider)
self.editClosure1of1 = editClosure1of1
singleSlider.translatesAutoresizingMaskIntoConstraints = false
singleSlider.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 50.0).isActive = true
singleSlider.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -50.0).isActive = true
singleSlider.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -32.0).isActive = true
singleSlider.tag = 0
singleSlider.addTarget(self, action: #selector(self.sliderChanged(_:withEvent:)), for: .valueChanged)
}
您可以將setup
聲明為一個閉包,它使用剛創建的實例作為參數。 例:
class ControlPanel: UIView {
let title: String
var someProperty: Int = 0
init(title: String, setup: ((ControlPanel) -> Void)? = nil) {
self.title = title
super.init(frame: CGRect())
if let setup = setup {
setup(self)
}
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
這可以稱為
let panel = ControlPanel(title: "title") {
$0.someProperty = 5
}
但是,只有在實例完全初始化后才能調用閉包,這意味着someProperty
需要是一個變量,並且必須分配一個初始值。 因此,創建實例后進行自定義設置沒有太多優勢:
let panel = ControlPanel(title: "title")
panel.someProperty = 5
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