Array/Sequence Extension Swift for mapUnique function to get unique and distinct properties mapped from any data structure which inherits Sequence

Array+Extension.Swift

public extension Sequence {
    
    public func mapUnique<T: Equatable>(_ transform: (Iterator.Element) -> T) -> [T] {
        var result: [T] = []
        //takes O(n^2) time since T is not Hashable type
        for element in self {
            let transformedElement: T = transform(element)
            if result.contains(transformedElement) {
                continue
            }
            result.append(transformedElement)
        }
        
        return result
    }
    
    public func mapUnique<T: Hashable>(_ transform: (Iterator.Element) -> T) -> [T] {
        var result: [T] = []
        var tempSet = Set<T>()
        
        //takes O(n) time using Set
        for element in self {
            let transformedElement: T = transform(element)
            
            if tempSet.contains(transformedElement) {
                continue
            }
            result.append(transformedElement)
            tempSet.insert(transformedElement)
        }
        
        return result
    }

}


public extension Sequence where Iterator.Element: Equatable {
    
    public func unique() -> [Iterator.Element] {
        var result: [Iterator.Element] = []
        
        //takes O(n^2) time since element is not Hashable type
        for element in self {
            if result.contains(element) {
                continue
            }
            result.append(element)
        }
        
        return result
    }
    
}


public extension Sequence where Iterator.Element: Hashable {
    
    public func unique() -> [Iterator.Element] {
        var result: [Iterator.Element] = []
        var tempSet = Set<Iterator.Element>()
        
        //takes O(n) time using Set
        for element in self {
            if tempSet.contains(element) {
                continue
            }
            result.append(element)
            tempSet.insert(element)
        }
        
        return result
    } 
    
}

Here is an example. The output maintains same order as that of array.

Input:

class Data {
    var name: String!
    var id: Int!
    
    convenience init(name: String, id: Int) {
        self.init()
        self.name = name
        self.id = id
    }
}

let array = [Data(name: "ab", id: 23),
             Data(name: "ab", id: 24),
             Data(name: "cd", id: 25),
             Data(name: "ef", id: 26),
             Data(name: "ef", id: 27),
             Data(name: "ef", id: 28),
             Data(name: "gh", id: 29)]
let nameArray = array.mapUnique { $0.name }
print(nameArray)

Output:

["ab", "cd", "ef", "gh"]