Error - Variable binding in a condition requires an initializer

Question

Cant solve this error, need a little help. In fact I find understand this error and why its happening. Im using dictionary to create prefixes for my list.

func cretaeExtendedTableViewData() {
    // ...

    for country in self.countriesList {
        let countryKey = String(country.name.prefix(1)) // USA > U

        if var countryValues = countriesDictionary[countryKey] {
            countryValues.append(country)
            countriesDictionary[countryKey] = countryValues
        } else {
            // ...
        }
    }
}

Answer 1

Seems like you are trying to group countries by the first character of their names. Dictionary has a dedicate initializer for grouping elements of an array with the given condition:

let grouped = Dictionary(grouping: countriesList) {
    $0["name"]!.prefix(1)
}

example:

let countriesList = [
    ["name": "USA"],
    ["name": "UAE"],
    ["name": "Italy"],
    ["name": "Iran"]
]

let grouped = Dictionary(grouping: countriesList) {
    $0["name"]!.prefix(1)
}

print(grouped)

prints:

[  "I": [
         ["name": "Italy"],
         ["name": "Iran"]
  ], 
   "U": [
         ["name": "USA"],
         ["name": "UAE"]
  ]
]