How to avoid duplicate key error in swift when iterating over a dictionary

Question

I\'m practicing swift and I\'m trying to iterate over a Dictionary to print the key, but it gives me a

fatal error: Dictionary literal contains dupli

Answer 1

As others already said, you cannot create a dictionary where the same key does appear more then once.

That said I really like solution provided by luk2302 because if does offer a well structured approach.

Here I am just adding another solution.

Since the real information in your (wrong) dictionary is the value (not the key) what's the meaning of using a Dictionary?

You could simply use an array

let ages = [14, 15, 75, 43, 103, 87, 12]
ages.forEach { print($0) }

Answer 2

Each dictionary key MUST be unique

let people = ["age1":14, "age2":15, "age3":75, "age4":43, "age5":103, "age6":87, "age7":12]
for (key, value) in people {
    print(value)
}

Answer 3

Create a People struct or class and use instances of that in an array rather than a dictionary:

struct Person {
    var age : Int
}

let people = [Person(age: 14), Person(age: 15)] // and so on

for person in people {
    print(person)
}    

A dictionary is a mapping of a unique key to some value. Therefore what you previously did was not working because your key age was not unique. You can however use a different dictionary:

let people = [14: Person(age: 14), 15: Person(age: 15)] // and so on

for (key, value) in people {
    print("\(key) => \(value)")
}