实例方法
assign(to:
assign(to:on:)
将来自发布者的每个元素分配给对象的属性。
声明
func assign<Root>(
to keyPath: ReferenceWritableKeyPath<Root, Self.Output>,
on object: Root
) -> AnyCancellable
当
Failure
为 Never
时可用。返回值
AnyCancellable
实例。当您不再希望发布者自动分配属性时,请在此实例上调用 Cancellable/cancel()
。取消初始化此实例也将取消自动分配。
参数
keyPath
指示要分配的属性的键路径。请参阅
The Swift Programming Language
中的Key-Path Expression,了解如何使用键路径来指定对象的属性。object
包含该属性的对象。订阅者每次收到新值时都会分配对象的属性。
详述
如果您想在每次发布者生成值时设置给定属性,请使用 Publisher/assign(to:on:)
订阅者。
在此示例中,Publisher/assign(to:on:)
在 MyClass
的实例上设置 anInt
属性的值:
class MyClass {
var anInt: Int = 0 {
didSet {
print("anInt was set to: \(anInt)", terminator: "; ")
}
}
}
var myObject = MyClass()
let myRange = (0...2)
cancellable = myRange.publisher
.assign(to: \.anInt, on: myObject)
// Prints: "anInt was set to: 0; anInt was set to: 1; anInt was set to: 2"
可用版本
iOS 13.0+, iPadOS 13.0+, macOS 10.15+, Mac Catalyst 13.0+, tvOS 13.0+, watchOS 6.0+
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注:本文由纯净天空筛选整理自apple.com大神的英文原创作品 Optional.Publisher assign(to:on:)。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。