数组要求 'Element' 符合 'Equatable'

Question

I am writing an iOS App in Swift. I added a class SynchronizedArray . On its remove method I am getting an error:

Referencing instance method 'remove(obj:)' on 'Array' requires that 'Element' conform to 'Equatable'

I tried the solutions on the internet but not working.

Code:

 final class SynchronizedArray<Element> {
        var array: [Element]
        private let queue: DispatchQueue
        
    func remove(_ element:Element){
        queue.async(flags: .barrier) {
            self.array.remove(obj:element)
            //Error: Referencing instance method 'remove(obj:)' on 'Array' requires that 'Element' conform to 'Equatable'
        }
    }
    
}

fileprivate extension Array where Element: Equatable {
    
    // Remove first collection element that is equal to the given `object`:
    mutating func remove(obj: Element) {
        if let index = index(of: obj) {
            remove(at: index)
        }
    }
}

Answer 1

Your class should conform to Equatable and index(of:) is deprecated use firstIndex

final class SynchronizedArray<Element:Equatable> {
    var array: [Element] = []
        private let queue: DispatchQueue? = nil
        
    func remove(_ element:Element){
        queue?.async(flags: .barrier) {
            self.array.remove(obj:element)
            //Error: Referencing instance method 'remove(obj:)' on 'Array' requires that 'Element' conform to 'Equatable'
        }
    }
    
}

fileprivate extension Array where Element: Equatable {
    
    // Remove first collection element that is equal to the given `object`:
    mutating func remove(obj: Element) {
        if let index = firstIndex(of: obj) {
            remove(at: index)
        }
    }
}

Answer 2

Simply modify the class SynchronizedArray declaration and conform Element to Equatable like so,

final class SynchronizedArray<Element: Equatable> {
    //rest of the code...
}

This will resolve your initial issue.

Another issue will the pop up saying Class 'SynchronizedArray' has no initializers . That's because you haven't initialised the stored properties of the class . Use below code when defining the properties,

var array = [Element]()
private let queue = DispatchQueue.main //Initialize with whatever type of queue you want to use