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我正在看一些自動佈局庫的代碼。在這裏面,有一個由UIView的採用了協議:在協議的屬性聲明中,「get」是什麼意思?
extension UIView: Constrainable {}
extension UILayoutGuide: Constrainable {
// LayoutGuide doesn't have baseline anchors, so just use the bottom anchor
public var firstBaselineAnchor: NSLayoutYAxisAnchor {
return bottomAnchor
}
public var lastBaselineAnchor: NSLayoutYAxisAnchor {
return bottomAnchor
}
}
public protocol Constrainable {
var topAnchor: NSLayoutYAxisAnchor { get }
var bottomAnchor: NSLayoutYAxisAnchor { get }
var leftAnchor: NSLayoutXAxisAnchor { get }
var rightAnchor: NSLayoutXAxisAnchor { get }
var leadingAnchor: NSLayoutXAxisAnchor { get }
var trailingAnchor: NSLayoutXAxisAnchor { get }
var centerXAnchor: NSLayoutXAxisAnchor { get }
var centerYAnchor: NSLayoutYAxisAnchor { get }
var widthAnchor: NSLayoutDimension { get }
var heightAnchor: NSLayoutDimension { get }
var firstBaselineAnchor : NSLayoutYAxisAnchor { get }
var lastBaselineAnchor : NSLayoutYAxisAnchor { get }
}
什麼是空{ get }
完成?
你在說什麼空吸? –
請參閱[Swift編程語言:協議]中的「屬性要求」(https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Protocols.html#//apple_ref/doc/uid/) TP40014097-CH25-ID267)。 – Rob
[Swift中協議的只讀屬性]的可能重複(http://stackoverflow.com/questions/31358518/read-only-properties-of-protocols-in-swift) –