ios 用 Swift 比较类型
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Comparing types with Swift
提问by puttputt
I'm looking to do something like the following, but when I try to see if b == Test.self I get the error "Any class is not convertible to MirrorDisposition". How can I checked to see if a Type is equal to another type?
我正在做类似下面的事情，但是当我尝试查看 b == Test.self 时，我收到错误“任何类都不能转换为 MirrorDisposition”。如何检查一个类型是否等于另一个类型？
class Test {
}
var a = Test.self
var b : AnyClass = a
if(b == Test.self) {
println("yes")
}
else {
println("no")
}
回答by Martin R
Use the "identical to" operator ===:
使用“等同于”运算符===：
if b === Test.self {
print("yes")
}
else {
print("no")
}
This works because the type of a class it itself a class object and can therefore
be compared with ===.
这是有效的，因为类的类型本身就是一个类对象，因此可以与===.
It won't work with structs. Perhaps someone has a better answer that works for
all Swift types.
它不适用于structs。也许有人有一个更好的答案，适用于所有 Swift 类型。
回答by Long Pham
if b.isKindOfClass(Test) {
println("yes")
} else {
println("no")
}
Edit: Swift 3
编辑：斯威夫特 3
if b.isKind(of: Test.self) {
print("yes")
} else {
print("no")
}
try it :)
尝试一下 ：）
回答by Xiaojun
If you just want to compare the class types, then you can simply use NSStringFromClass to compare the class names as below:
如果您只想比较类类型，那么您可以简单地使用 NSStringFromClass 来比较类名，如下所示：
class Test {}
var a = Test.self
var b : AnyClass = a
if(NSStringFromClass(b) == NSStringFromClass(Test.self)) {
println("yes")
} else {
println("no")
}
If you want to find out or compare the type of an object, you can use "if ... is ... {}" syntax as code below:
如果你想找出或比较一个对象的类型，你可以使用“if ... is ... {}”语法作为下面的代码：
class Test { }
class Testb { }
var a = Test.self
let b : AnyObject = Testb()
if(b is Test) {
println("yes")
} else {
println("no")
}
If you want to do object to object equality check with == operator, you can make your Test class conforms to Equatable protocol. This can be extended to both Struct and Class types in Swift as explained in this NSHipster article: http://nshipster.com/swift-comparison-protocols/.
如果您想使用 == 运算符进行对象到对象的相等性检查，您可以使您的 Test 类符合 Equatable 协议。这可以扩展到 Swift 中的 Struct 和 Class 类型，如这篇 NSHipster 文章中所述：http://nshipster.com/swift-comparison-protocols/ 。
You code then can be written as below, please note: this is object equality checking, so you cannot define b as AnyClass, you need to instead define as AnyObject.
然后你的代码可以写成如下，请注意：这是对象相等性检查，所以你不能定义b为AnyClass，你需要定义为AnyObject。
class Test: Equatable { }
// MARK: Equatable
func ==(lhs: Test, rhs: Test) -> Bool {
return ObjectIdentifier(lhs) == ObjectIdentifier(rhs)
}
var a = Test()
var b : AnyObject = a
if((b as Test) == a) {
println("yes")
} else {
println("no")
}
