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Equatable in Swift


Equatable in Swift

By : Comhk
Date : November 22 2020, 02:59 PM
will be helpful for those in need Exactly what it says. Move the operator function definition outside of the extension. It's done at a global scope.
code :


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Comparing dictionaries containing actually equatable types, based on non-equatable data structures

Comparing dictionaries containing actually equatable types, based on non-equatable data structures


By : Abir Sm
Date : March 29 2020, 07:55 AM
like below fixes the issue The == operator for dictionaries requires that both Key and Value type conform to Equatable.
You have implemented a (restricted) == operator for SortedList. But implementing a == operator for a type does not make that type Equatable automatically. The conformance must be declared explicitly.
code :
func ==<Key : Equatable, T : Equatable>(lhs: [Key : SortedList<T>], rhs: [Key : SortedList<T>]) -> Bool {
    // ...
}
Why doesn't array conform to Equatable, when its items are Equatable in Swift?

Why doesn't array conform to Equatable, when its items are Equatable in Swift?


By : Anton Zhyravlev
Date : March 29 2020, 07:55 AM
help you fix your problem Swift 4.1 update:
With the introduction of conditional conformance in Swift 4.1, Array now conforms to Equatable, so the issue should be resolved without the need to resort to any workarounds.
code :
import Foundation

struct Post: Equatable {
    let text: String
}

enum Result<T>: Equatable where T: Equatable {
    case success(result: T)
    case error
}
func test() {

    // Test 1: Check Post type for equality: OK
    let post1 = Post(text: "post")
    let post2 = Post(text: "post")

    if post1 == post2 {
        print("equal posts")
    }

    // Test 2: Check [Post] type for equality: OK
    let arrayOfPosts1 = [post1, post2]
    let arrayOfPosts2 = [post1, post2]

    if arrayOfPosts1 == arrayOfPosts2 {
        print("equal arrays of post")
    }

    // Test 3: Check Result<Post> type for equality: OK
    let result1 = Result<Post>.success(result: post1)
    let result2 = Result<Post>.success(result: post2)

    if result1 == result2 {
        print("equal results of post")
    }

    // Test 4: Check Result<[Post]> type for equality: OK
    let arrayResult1: Result<[Post]> = Result<[Post]>.success(result: arrayOfPosts1)
    let arrayResult2: Result<[Post]> = Result<[Post]>.success(result: arrayOfPosts2)

    if arrayResult1 == arrayResult2 {
        print("equal results of array of posts")
    }
}
test()
/*
 prints:
 equal posts
 equal arrays of post
 equal results of post
 equal results of array of posts
*/
Equatable with enum - Swift

Equatable with enum - Swift


By : user3135669
Date : March 29 2020, 07:55 AM
I hope this helps . The enum case CannotFetch has an associated value of type String. That means, when the enum case is set to CannotFetch, a specific String is associated with that case. Read through the official Swift documentation about Enumerations if you need to understand Associated Values.
The func ==() method is a so called Equivalence Operator. You can read more about it in the official Swift documentation about Advanced Operators.
code :
let enumOne = ErrorAPI.CannotFetch("Hi")
let enumTwo = ErrorAPI.CannotFetch("Hello")

if enumOne != enumTwo {
    print("They are not equal!")
} else {
    print("They are equal")
}
Understanding Equatable in swift 3?

Understanding Equatable in swift 3?


By : Alejandro Santiago
Date : March 29 2020, 07:55 AM
wish helps you By definition, two enums of the same type are equal if they are of the same case. Thus .image is equal to .image, for example. That is why you are able to test enum instances against one another using the == operator to find out what case something is. Indeed, this fact is sort of the point of enums.
(This, by the way, is also why enums cannot have stored properties. Two .image instances with different stored values for the same property would not be equal. And that would completely defeat the purpose of enums.)
Swift Equatable on a protocol

Swift Equatable on a protocol


By : jjefferies
Date : March 29 2020, 07:55 AM
it fixes the issue If you directly implement Equatable on a protocol, it will not longer be usable as a type, which defeats the purpose of using a protocol. Even if you just implement == functions on protocols without Equatable conformance, results can be erroneous. See this post on my blog for a demonstration of these issues:
https://khawerkhaliq.com/blog/swift-protocols-equatable-part-one/
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