Convert Swift Array to Dictionary with indexes [duplicate]
I'm using Xcode 6.4
I have an array of UIViews and I want to convert to a Dictionary with keys "v0", "v1"...
. Like so:
var dict = [String:UIView]()
for (index, view) in enumerate(views) {
dict["v\(index)"] = view
}
dict //=> ["v0": <view0>, "v1": <view1> ...]
This works, but I'm trying to do this in a more functional style. I guess it bothers me that I have to create the dict
variable. I would love to use enumerate()
and reduce()
like so:
reduce(enumerate(views), [String:UIView]()) { dict, enumeration in
dict["v\(enumeration.index)"] = enumeration.element // <- error here
return dict
}
This feels nicer, but I'm getting the error: Cannot assign a value of type 'UIView' to a value of type 'UIView?'
I have tried this with objects other an UIView
(ie: [String] -> [String:String]
) and I get the same error.
Any suggestions for cleaning this up?
Solution 1:
try like this:
reduce(enumerate(a), [String:UIView]()) { (var dict, enumeration) in
dict["\(enumeration.index)"] = enumeration.element
return dict
}
Xcode 8 • Swift 2.3
extension Array where Element: AnyObject {
var indexedDictionary: [String:Element] {
var result: [String:Element] = [:]
for (index, element) in enumerate() {
result[String(index)] = element
}
return result
}
}
Xcode 8 • Swift 3.0
extension Array {
var indexedDictionary: [String: Element] {
var result: [String: Element] = [:]
enumerated().forEach({ result[String($0.offset)] = $0.element })
return result
}
}
Xcode 9 - 10 • Swift 4.0 - 4.2
Using Swift 4 reduce(into:)
method:
extension Collection {
var indexedDictionary: [String: Element] {
return enumerated().reduce(into: [:]) { $0[String($1.offset)] = $1.element }
}
}
Using Swift 4 Dictionary(uniqueKeysWithValues:)
initializer and passing a new array from the enumerated collection:
extension Collection {
var indexedDictionary: [String: Element] {
return Dictionary(uniqueKeysWithValues: enumerated().map{(String($0),$1)})
}
}