Could someone please help me understand why .sort is giving me a new type?
I have a dictionary like this:
var wordDict : [String : [String]]
Which contains unorganized keys:
["H": ["Hal", "Hamilton", "Hank", "Hans", "Harmon", "Harold", "Harris", "Harry", "Hartmann", "Harv", "Harvey", "Hazel", "Heather", "Hector", "Heidi", "Hein", "Heinrich", "Heinz", "Helen", "Helge", "Henry", "Herb", "Herbert", "Herman", "Herve", "Hienz", "Hilda", "Hillary", "Hillel", "Himawan", "Hirofumi", "Hirotoshi", "Hiroyuki", "Hitoshi", "Hohn", "Holly", "Hon", "Honzo", "Horst", "Hotta", "Howard", "Hsi", "Hsuan", "Huashi", "Hubert", "Huey", "Hugh", "Hughes", "Hui", "Hume", "Hunter", "Hurf", "Hwa", "Hy"], "V": ["Vadim", "Val", "Valentin", "Valeria", "Valerie", "Van", "Vance", "Varda", "Vassos", "Vaughn", "Venkata", "Vern", "Vernon", "Vic", "Vice", "Vick", "Vicki", "Vickie", "Vicky", "Victor", "Victoria", "Vidhyanath", "Vijay", "Vilhelm", "Vince", "Vincent", "Vincenzo", "Vinod", "Vishal", "Vistlik", "Vivek", "Vladimir", "Vladislav"], "D": ["Dale", "Dalton", "Damon", "Damone", "Dan", "Dana", "Dani", "Daniel", "Daniele", "Danielle", "Dannie", "Danny", "Darci", "Daren", "Darin", "Darrell", "Darren", "Darryl", "Daryl", "Dave", "David", "Dawn", "Dawson", "Dean", "Deb", "Debbie", "Debi", "Deborah", "Deirdre", "Del", "Delbert", "Denis", "Dennis", "Derek", "Devon", "Dewey", "Diana", "Diane", "Dick", "Dieter", "Dimetry", "Dimitry", "Dion", "Dirk", "Dominic", "Dominick", "Don", "Donal", "Donald", "Donn", "Donna", "Donne", "Donnie", "Donovan", "Dori", "Dorian", "Dorothy", "Dory", "Doug", "Douglas", "Doyle", "Drew", "Duane", "Duke", "Duncan", "Dustin", "Dwayne", "Dwight", "Dylan"]... and so on
When I call .sort on my dictionary like this:
let sortDict = wordDict.sort { $0.0 < $1.0 }
sortDict now has an unexpected type [(String:[String])], which looks like this:
[("A", ["Aaron", "Adam", "Adlai", "Adrian", "Agatha", "Ahmed", "Ahmet", "Aimee", "Al", "Alain", "Alan", "Alastair", "Albert", "Alberto", "Alejandro", "Alex", "Alexander", "Alexis", "Alf", "Alfred", "Alison", "Allan", "Allen", "Alvin", "Amanda", "Amarth", "Amedeo", "Ami", "Amigo", "Amir", "Amos", "Amy", "Anatole", "Anatoly", "Anderson", "Andre", "Andrea", "Andreas", "Andrew", "Andries", "Andy", "Angela", "Angus", "Anita", "Ann", "Anna", "Annard", "Anne", "Annie", "Anthony", "Anton", "Antonella", "Antonio", "Antony", "Archie", "Ariel", "Arlene", "Arne", "Arnold", "Art", "Arthur", "Audrey", "Avery", "Axel"])... and so on
So it's organized them, but for some reason I have a new type.
Why is sort giving me a new type? Also, what is the proper way to sort my dictionary?
Note that dictionary is unordered collection of keys and values.
From documentation it states the following,
A dictionary stores associations between keys of the same type and values of the same type in an collection with no defined ordering. Each value is associated with a unique key, which acts as an identifier for that value within the dictionary. Unlike items in an array, items in a dictionary do not have a specified order. You use a dictionary when you need to look up values based on their identifier, in much the same way that a real-world dictionary is used to look up the definition for a particular word.
So, you cannot have sorted dictionary. Even if you sort the keys and assign it one by one, there is no guarantee that the key and value remains sorted as assigned order.
The only way, you could do is sort the keys and then extract values one by one for each sorted key.
let myDict = ["H": ["Hal", "Hamilton", "Hank", "Hans", "Harmon", "Harold", "Harris", "Harry", "Hartmann", "Harv", "Harvey", "Hazel", "Heather", "Hector", "Heidi", "Hein", "Heinrich", "Heinz", "Helen", "Helge", "Henry", "Herb", "Herbert", "Herman", "Herve", "Hienz", "Hilda", "Hillary", "Hillel", "Himawan", "Hirofumi", "Hirotoshi", "Hiroyuki", "Hitoshi", "Hohn", "Holly", "Hon", "Honzo", "Horst", "Hotta", "Howard", "Hsi", "Hsuan", "Huashi", "Hubert", "Huey", "Hugh", "Hughes", "Hui", "Hume", "Hunter", "Hurf", "Hwa", "Hy"], "V": ["Vadim", "Val", "Valentin", "Valeria", "Valerie", "Van", "Vance", "Varda", "Vassos", "Vaughn", "Venkata", "Vern", "Vernon", "Vic", "Vice", "Vick", "Vicki", "Vickie", "Vicky", "Victor", "Victoria", "Vidhyanath", "Vijay", "Vilhelm", "Vince", "Vincent", "Vincenzo", "Vinod", "Vishal", "Vistlik", "Vivek", "Vladimir", "Vladislav"], "D": ["Dale", "Dalton", "Damon", "Damone", "Dan", "Dana", "Dani", "Daniel", "Daniele", "Danielle", "Dannie", "Danny", "Darci", "Daren", "Darin", "Darrell", "Darren", "Darryl", "Daryl", "Dave", "David", "Dawn", "Dawson", "Dean", "Deb", "Debbie", "Debi", "Deborah", "Deirdre", "Del", "Delbert", "Denis", "Dennis", "Derek", "Devon", "Dewey", "Diana", "Diane", "Dick", "Dieter", "Dimetry", "Dimitry", "Dion", "Dirk", "Dominic", "Dominick", "Don", "Donal", "Donald", "Donn", "Donna", "Donne", "Donnie", "Donovan", "Dori", "Dorian", "Dorothy", "Dory", "Doug", "Douglas", "Doyle", "Drew", "Duane", "Duke", "Duncan", "Dustin", "Dwayne", "Dwight", "Dylan"]]
let sortedKeys = myDict.keys.sort()
sortedKeys.forEach { aKey in
print(myDict[aKey])
}
If you look in swift header file, you will see the following delcaration for the protocol SequenceType.
extension SequenceType where Self.Generator.Element : Comparable {
/// Return an `Array` containing the sorted elements of `source`.
///
/// The sorting algorithm is not stable (can change the relative order of
/// elements that compare equal).
///
/// - Requires: The less-than operator (`func <`) defined in
/// the `Comparable` conformance is a
/// [strict weak ordering](http://en.wikipedia.org/wiki/Strict_weak_order#Strict_weak_orderings)
/// over the elements in `self`.
@warn_unused_result
public func sort() -> [Self.Generator.Element]
}
Here sort method returns [Self.Generator.Element]. In you case you have Sequence type of Dict ie [String: [String]] and so the Element type is (Key, Value) => (String, [String]) which when sorted should return [(Key, Value)] => [(String, [String])]. And that is what you get.
Or you could create some struct or class type which has key as identifiers and then values would be some other properties. Then you could add then to the an array.
Here is an example of how you could create a sectioned tableview with the data above,
class ViewController: UIViewController {
internal class MyView: UIView, UITableViewDataSource {
let myDict = ["H": ["Hal", "Hamilton", "Hank", "Hans", "Harmon", "Harold", "Harris", "Harry", "Hartmann", "Harv", "Harvey", "Hazel", "Heather", "Hector", "Heidi", "Hein", "Heinrich", "Heinz", "Helen", "Helge", "Henry", "Herb", "Herbert", "Herman", "Herve", "Hienz", "Hilda", "Hillary", "Hillel", "Himawan", "Hirofumi", "Hirotoshi", "Hiroyuki", "Hitoshi", "Hohn", "Holly", "Hon", "Honzo", "Horst", "Hotta", "Howard", "Hsi", "Hsuan", "Huashi", "Hubert", "Huey", "Hugh", "Hughes", "Hui", "Hume", "Hunter", "Hurf", "Hwa", "Hy"], "V": ["Vadim", "Val", "Valentin", "Valeria", "Valerie", "Van", "Vance", "Varda", "Vassos", "Vaughn", "Venkata", "Vern", "Vernon", "Vic", "Vice", "Vick", "Vicki", "Vickie", "Vicky", "Victor", "Victoria", "Vidhyanath", "Vijay", "Vilhelm", "Vince", "Vincent", "Vincenzo", "Vinod", "Vishal", "Vistlik", "Vivek", "Vladimir", "Vladislav"], "D": ["Dale", "Dalton", "Damon", "Damone", "Dan", "Dana", "Dani", "Daniel", "Daniele", "Danielle", "Dannie", "Danny", "Darci", "Daren", "Darin", "Darrell", "Darren", "Darryl", "Daryl", "Dave", "David", "Dawn", "Dawson", "Dean", "Deb", "Debbie", "Debi", "Deborah", "Deirdre", "Del", "Delbert", "Denis", "Dennis", "Derek", "Devon", "Dewey", "Diana", "Diane", "Dick", "Dieter", "Dimetry", "Dimitry", "Dion", "Dirk", "Dominic", "Dominick", "Don", "Donal", "Donald", "Donn", "Donna", "Donne", "Donnie", "Donovan", "Dori", "Dorian", "Dorothy", "Dory", "Doug", "Douglas", "Doyle", "Drew", "Duane", "Duke", "Duncan", "Dustin", "Dwayne", "Dwight", "Dylan"]]
override init(frame: CGRect) {
super.init(frame: frame)
let tableView = UITableView(frame: frame)
tableView.autoresizingMask = [UIViewAutoresizing.FlexibleHeight, UIViewAutoresizing.FlexibleWidth]
tableView.dataSource = self
addSubview(tableView)
}
required init?(coder aDecoder: NSCoder) {
fatalError("Not supported")
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return myDict.keys.count
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let keys = myDict.keys.sort()
let keyForSection = keys[section]
let rowCount = myDict[keyForSection]!.count
return rowCount
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cellIdentifier = "CellIdentifier"
var cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier)
if cell == nil {
cell = UITableViewCell(style: UITableViewCellStyle.Default, reuseIdentifier: cellIdentifier)
}
let keys = myDict.keys.sort()
let keyForSection = keys[indexPath.section]
let rowItem = myDict[keyForSection]!.sort()[indexPath.row]
cell?.textLabel?.text = rowItem
return cell!
}
func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
let keys = myDict.keys.sort()
let keyForSection = keys[section]
return keyForSection
}
func sectionIndexTitlesForTableView(tableView: UITableView) -> [String]? {
let keys = myDict.keys.sort()
return keys
}
}
override func viewDidLoad() {
super.viewDidLoad()
edgesForExtendedLayout = UIRectEdge.None
let myView = MyView(frame: view.bounds)
myView.autoresizingMask = [.FlexibleHeight, .FlexibleWidth]
view.addSubview(myView)
}
}
The above example only shows how you can do it. It is not good in performance, since it sorts at every tableview cellForRowAtIndexPath method and does some calculation on each data source method. You can refine that yourself :)