符合多种协议的类型

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最佳答案

This should work:

var identityToken: NSObjectProtocol & NSCopying & NSCoding

Note you have to use NSObjectProtocol instead of NSObject in swift.

Here are some additional examples:

Array of objects conforming to multiple protocols:

var array: [NSObjectProtocol & NSCopying & NSCoding]

Function with a parameter that conforms to multiple protocols:

func foo(param: NSObjectProtocol & NSCopying & NSCoding) {


}

For Swift version before 3.1, use:

var identityToken: (NSObjectProtocol, NSCopying, NSCoding)

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The above answer from conner is correct, however you often should implement a separate protocol that itself inherits from the other protocols, and allows you more flexibility, should you want to add additional protocol methods later or change the top level protocols.

internal protocol MyOtherProtocol : NSObjectProtocol, NSCopying, NSCoding {
func someOtherNecessaryMethod()
}

Then utilized:

var identityToken : MyOtherProtocol

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Swift 3

var idToken: NSObjectProtocol & NSCopying & NSCoding


func foo(_ delegateAndDataSource: UICollectionViewDelegate & UICollectionViewDataSource) { ... }

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For generics this works as well:

func setCollectionViewDataSourceDelegate<D: UICollectionViewDataSource & UICollectionViewDelegate>

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Seems like you could also type-alias the composite protocols, which may come in handy if you plan on using the same combination of protocol multiple times.

typealias IDToken = NSObjectProtocol & NSCopying & NSCoding

Same examples as given in the accepted answer, using a type-alias:

var idToken: IDToken


var array: [IDToken] = []


func foo(param: IDToken) { ... }