class book{
var nameOfBook: String!
}
var englishBooks=[book(),book(),book()]
var arr = englishBooks.filter {
contains($0.nameOfBook, "rt")
}
I'm using this filter but with error cannot invoke filter with an argument
contains() checks if a sequence contains a given element, e.g.
if a String contains a given Character.
If your intention is to find all books where the name contains the substring "rt", then you can use rangeOfString():
var arr = englishBooks.filter {
$0.nameOfBook.rangeOfString("rt") != nil
}
or for case-insensitive comparison:
var arr = englishBooks.filter {
$0.nameOfBook.rangeOfString("rt", options: .CaseInsensitiveSearch) != nil
}
As of Swift 2, you can use
nameOfBook.containsString("rt") // or
nameOfBook.localizedCaseInsensitiveContainsString("rt")
and in Swift 3 this is
nameOfBook.contains("rt") // or
nameOfBook.localizedStandardContains("rt") // or
nameOfBook.range(of: "rt", options: .caseInsensitive) != nil
Sorry this is an old thread. Change you code slightly to properly init your variable 'nameOfBook'.
class book{
var nameOfBook: String!
init(name: String) {
nameOfBook = name
}
}
Then we can create an array of books.
var englishBooks = [book(name: "Big Nose"), book(name: "English Future
Prime Minister"), book(name: "Phenomenon")]
The array's 'filter' function takes one argument and some logics, 'contains' function can take a simplest form of a string you are searching for.
let list1 = englishBooks.filter { (name) -> Bool in
name.contains("English")
}
You can then print out list1 like so:
let list2 = arr1.map({ (book) -> String in
return book.nameOfBook
})
print(list2)
// print ["English Future Prime Minister"]
Above two snippets can be written short hand like so:
let list3 = englishBooks.filter{ ($0.nameOfBook.contains("English")) }
print(list3.map({"\($0.nameOfBook!)"}))
SWIFT 4.0
In order to filter objects and get resultant array you can use this
self.resultArray = self.upcomingAuctions.filter {
$0.auctionStatus == "waiting"
}
in case you want to delete an interval of object which has specific IDs (matchIDsToDelete) from an array of object (matches)
var matches = [Match]
var matchIDsToDelete = [String]
matches = matches.filter { !matchIDsToDelete.contains($0.matchID) }
2020 | SWIFT 5.1:
short answer:
books.filter { $0.alias.range(of: filterStr, options: .caseInsensitive) != nil }
long sample:
public filterStr = ""
public var books: [Book] = []
public var booksFiltered: [Book] {
get {
(filterStr.isEmpty )
? books
: books.filter { $0.alias.range(of: filterStr, options: .caseInsensitive) != nil }
}
}
I think this is more useful for lack of wrong typing situation.
englishBooks.filter( { $0.nameOfBook.range(of: searchText, options: .caseInsensitive) != nil}
In Swift 4.2 use the remove(where:) functionality. filter isn't doing well with memory, remove(where:) does the job better.
To do what you want:
englishBooks.removeAll { !$0.nameOfBook.contains("English") }
Related
kindly note that my question is specific to Swift 4 syntax. I have a bulky/large array of Strings and I want to filter it for getting all values in it which are started with some specific characters/substring. That means I need each String in my array which matches to started with some substring. I found different links which gives me code for Objective-C and I am unable to implement it in Swift 4 because of that methods are not available in Swift 4. I solved my question manually by iterating my array in for loop but it gives very slow result So I don't want to use any loop here, So any help will useful. Thanks in advance. See my code below:
func search() -> Void {
var dummyStringsArray:[String] = ["Hotel Restaurants","Restaurants","Certified Green Restaurant(R)","Japnies Food Restauarants","Grill Restaurants","Restaurant Equipment","Wholsale Restaurant Fixtures","American Food","Wholsale Restaurant Supplies","Veg Restaurants","Barbecue Restaurants","Non-Veg Restaurants"]
var displayDataArray:[String] = []
let searchString:NSString = (textField.text!).lowercased() as NSString
for string in self.dummyStringsArray {
let mainString:NSString = string.lowercased() as NSString
if mainString.length >= searchString.length {
let compareString = String(mainString.substring(to: searchString.length))
if searchString as String == compareString {
displayDataArray.append(string)
}
}
}
}
So if I entered text in textField as 're' then it should return displayDataArray containing values like "Restaurants", "Restaurant Equipment".
I think you can't do this without any loop because you need to go through all the elements
But I can offer you more elegant solution with filter function:
func search() -> Void {
let dummyStringsArray:[String] = ["Hotel Restaurants","Restaurants","Certified Green Restaurant(R)","Japnies Food Restauarants","Grill Restaurants","Restaurant Equipment","Wholsale Restaurant Fixtures","American Food","Wholsale Restaurant Supplies","Veg Restaurants","Barbecue Restaurants","Non-Veg Restaurants"]
let searchString: String = (textField.text!).lowercased()
let displayDataArray: [String] = dummyStringsArray.filter({ String($0.prefix(searchString.count)).lowercased() == searchString })
}
You will probably get the best performance using range(of:options:) while passing in the options of .caseInsensitive and .anchored.
func search() -> Void {
let dummyStringsArray = ["Hotel Restaurants","Restaurants","Certified Green Restaurant(R)","Japnies Food Restauarants","Grill Restaurants","Restaurant Equipment","Wholsale Restaurant Fixtures","American Food","Wholsale Restaurant Supplies","Veg Restaurants","Barbecue Restaurants","Non-Veg Restaurants"]
let searchString = textField.text!
let displayDataArray = dummyStringsArray.filter { $0.range(of: searchString, options: [ .caseInsensitive, .anchored ]) != nil }
}
I have a long string in swift3 and want to check if it contains word1 and word2. It could also be more than 2 search words. I found out following solution:
var Text = "Hello Swift-world"
var TextArray = ["Hello", "world"]
var count = 0
for n in 0..<TextArray.count {
if (Text.contains(TextArray[n])) {
count += 1
}
}
if (count == TextArray.count) {
print ("success")
}
But this seems very complicated, is there not an easier way to solve this? (Xcode8 and swift3)
If you are looking for less code:
let text = "Hello Swift-world"
let wordList = ["Hello", "world"]
let success = !wordList.contains(where: { !text.contains($0) })
print(success)
It is also a little more efficient than your solution because
the contains method returns as soon as a "not contained" word
is found.
As of Swift 4 or later, you can use allSatisfy:
let success = wordList.allSatisfy(text.contains)
A more Swifty solution that will stop searching after it found a non-existent word:
var text = "Hello Swift-world"
var textArray = ["Hello", "world"]
let match = textArray.reduce(true) { !$0 ? false : (text.range(of: $1) != nil ) }
Another way to do it which stops after it found a non-match:
let match = textArray.first(where: { !text.contains($0) }) == nil
Another possibility is regular expressions:
// *'s are wildcards
let regexp = "(?=.*Hello*)(?=.*world*)"
if let range = Text.range(of:regexp, options: .regularExpression) {
print("this string contains Hello world")
} else {
print("this string doesn't have the words we want")
}
I have a string in Swift that looks like this:
["174580798","151240033","69753978","122754394","72373738","183135789","178841809","84104360","122823486","184553211","182415131","70707972"]
I need to convert it into an NSArray.
I've looked at other methods on SO but it is breaking each character into a separate array element, as opposed to breaking on the comma. See: Convert Swift string to array
I've tried to use the map() function, I've also tried various types of casting but nothing seems to come close.
Thanks in advance.
It's probably a JSON string so you can try this
let string = "[\"174580798\",\"151240033\",\"69753978\",\"122754394\",\"72373738\",\"183135789\",\"178841809\",\"84104360\",\"122823486\",\"184553211\",\"182415131\",\"70707972\"]"
let data = string.dataUsingEncoding(NSUTF8StringEncoding)!
let jsonArray = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions(), error: nil) as! [String]
as the type [String] is distinct you can cast it forced
Swift 3+:
let data = Data(string.utf8)
let jsonArray = try! JSONSerialization.jsonObject(with: data) as! [String]
The other two answers are working, although SwiftStudiers isn't the best regarding performance. vadian is right that your string most likely is JSON. Here I present another method which doesn't involve JSON parsing and one which is very fast:
import Foundation
let myString = "[\"174580798\",\"151240033\",\"69753978\",\"122754394\",\"72373738\",\"183135789\",\"178841809\",\"84104360\",\"122823486\",\"184553211\",\"182415131\",\"70707972\"]"
func toArray(var string: String) -> [String] {
string.removeRange(string.startIndex ..< advance(string.startIndex, 2)) // Remove first 2 chars
string.removeRange(advance(string.endIndex, -2) ..< string.endIndex) // Remote last 2 chars
return string.componentsSeparatedByString("\",\"")
}
toArray(myString) // ["174580798", "151240033", "69753978", ...
You probably want the numbers though, you can do this in Swift 2.0:
toArray(myString).flatMap{ Int($0) } // [174'580'798, 151'240'033, 69'753'978, ...
which returns an array of Ints
EDIT: For the ones loving immutability and functional programming, have this solution:
func toArray(string: String) -> [String] {
return string[advance(string.startIndex, 2) ..< advance(string.endIndex, -2)]
.componentsSeparatedByString("\",\"")
}
or this:
func toArray(string: String) -> [Int] {
return string[advance(string.startIndex, 2) ..< advance(string.endIndex, -2)]
.componentsSeparatedByString("\",\"")
.flatMap{ Int($0) }
}
Try this. I've just added my function which deletes any symbols from string except numbers. It helps to delete " and [] in your case
var myString = "[\"174580798\",\"151240033\",\"69753978\",\"122754394\",\"72373738\",\"183135789\",\"178841809\",\"84104360\",\"122823486\",\"184553211\",\"182415131\",\"70707972\"]"
var s=myString.componentsSeparatedByString("\",\"")
var someArray: [String] = []
for i in s {
someArray.append(deleteAllExceptNumbers(i))
}
println(someArray[0]);
func deleteAllExceptNumbers(str:String) -> String {
var rez=""
let digits = NSCharacterSet.decimalDigitCharacterSet()
for tempChar in str.unicodeScalars {
if digits.longCharacterIsMember(tempChar.value) {
rez += tempChar.description
}
}
return rez.stringByReplacingOccurrencesOfString("\u{22}", withString: "")
}
Swift 1.2:
If as has been suggested you are wanting to return an array of Int you can get to that from myString with this single concise line:
var myArrayOfInt2 = myString.componentsSeparatedByString("\"").map{$0.toInt()}.filter{$0 != nil}.map{$0!}
In Swift 2 (Xcode 7.0 beta 5):
var myArrayOfInt = myString.componentsSeparatedByString("\"").map{Int($0)}.filter{$0 != nil}.map{$0!}
This works because the cast returns an optional which will be nil where the cast fails - e.g. with [, ] and ,. There seems therefore to be no need for other code to remove these characters.
EDIT: And as Kametrixom has commented below - this can be further simplified in Swift 2 using .flatMap as follows:
var myArrayOfInt = myString.componentsSeparatedByString("\"").flatMap{ Int($0) }
Also - and separately:
With reference to Vadian's excellent answer. In Swift 2 this will become:
// ...
do {
let jsonArray = try NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions()) as! [String]
} catch {
_ = error // or do something with the error
}
I am using Swift 1.2 in Xcode 6.3.1
Following is my Person struct
struct Person {
let age: Int
init?(age: Int) { //Failable init
if age > 100 { return nil }
self.age = age
}
}
I am having a list of ages against which I have to make Person Objects.
I have made playground file.
let arr = Array(1...150) //Sample set of ages against which Person is created
var personList: [Person]!
and
personList = arr.map({ (val: Int) -> Person? in
return Person(age: val) //Makes object of type Person?
}).filter {
$0 != nil
}.map {
return $0!
}
Here I have uses map - filter - map because the first map invokes failable intializer, (hence it returns Person?) and personList is of type [Person].
Hence second function filters all the non nil objects and third map forcefully opens to optional therby making Person? to Person.
Is there a more easy/readable way out ? Chaining map-filter-map definitely seems to be an overkill for this
You can use flatMap to get rid of any nils in the array, this tutorial discusses the method in length, but the following will work best:
let personList = arr.flatMap { Person(age: $0) }
Note: This answer was given for Swift 1.2, the current
version at the time the question was posted. Since Swift 2 there is a better solution, see #Jeremie's answer.
I don't know of a built-in function that combines filter()
and map(). You can write the code slightly more compact using
the shorthand argument $0 in all closures:
let personList = arr.map { Person(age: $0) }
.filter { $0 != nil }
.map { $0! }
Of course you can define your own extension method which maps the
array elements and keeps only the non-nil results:
extension Array {
func optmap<U>(transform: T -> U?) -> [U] {
var result : [U] = []
for elem in self {
if let mapped = transform(elem) {
result.append(mapped)
}
}
return result
}
}
and then use it as
let personList = arr.optmap { Person(age: $0) }
You can use compactMap which is better that flatMap in this case to remove any nils in the array:
let personList = arr.compactMap { Person(age: $0) }
The Swift document declared:
Returns an array containing the non-nil results of calling the given
transformation with each element of this sequence.
So I am trying to get the Actual Variable Name as String in Swift, but have not found a way to do so... or maybe I am looking at this problem and solution in a bad angle.
So this is basically what I want to do:
var appId: String? = nil
//This is true, since appId is actually the name of the var appId
if( appId.getVarName = "appId"){
appId = "CommandoFurball"
}
Unfortunately I have not been able to find in apple docs anything that is close to this but this:
varobj.self or reflect(var).summary
however, this gives information of what is inside the variable itself or the type of the variable in this case being String and I want the Actual name of the Variable.
This is officially supported in Swift 3 using #keyPath()
https://github.com/apple/swift-evolution/blob/master/proposals/0062-objc-keypaths.md
Example usage would look like:
NSPredicate(format: "%K == %#", #keyPath(Person.firstName), "Wendy")
In Swift 4 we have something even better: \KeyPath notation
https://github.com/apple/swift-evolution/blob/master/proposals/0161-key-paths.md
NSPredicate(format: "%K == %#", \Person.mother.firstName, "Wendy")
// or
let keyPath = \Person.mother.firstName
NSPredicate(format: "%K == %#", keyPath, "Andrew")
The shorthand is a welcome addition, and being able to reference keypaths from a variable is extremely powerful
As per the updated from this answer, it is supported in Swift 3 via #keyPath
NSPredicate(format: "%K == %#", #keyPath(Person.firstName), "Andrew")
This is my solution
class Test {
var name: String = "Ido"
var lastName: String = "Cohen"
}
let t = Test()
let mirror = Mirror(reflecting: t)
for child in mirror.children {
print(child.label ?? "")
}
print will be
name
lastName
This works:
struct s {
var x:Int = 1
var y:Int = 2
var z:Int = 3
}
var xyz = s()
let m = Mirror(reflecting: xyz)
print(m.description)
print(m.children.count)
for p in m.children {
print(p.label as Any)
}
I've come up with a swift solution, however unfortunately it doesn't work with Ints, Floats, and Doubles I believe.
func propertyNameFor(inout item : AnyObject) -> String{
let listMemAdd = unsafeAddressOf(item)
let propertyName = Mirror(reflecting: self).children.filter { (child: (label: String?, value: Any)) -> Bool in
if let value = child.value as? AnyObject {
return listMemAdd == unsafeAddressOf(value)
}
return false
}.flatMap {
return $0.label!
}.first ?? ""
return propertyName
}
var mutableObject : AnyObject = object
let propertyName = MyClass().propertyNameFor(&mutableObject)
It compares memory addresses for an object's properties and sees if any match.
The reason it doesn't work for Ints, Floats, and Doubles because they're not of type anyobject, although you can pass them as anyobject, when you do so they get converted to NSNumbers. therefore the memory address changes. they talk about it here.
For my app, it didn't hinder me at all because I only needed it for custom classes. So maybe someone will find this useful. If anyone can make this work with the other datatypes then that would be pretty cool.
Completing the accepted answer for extensions:
The property needs to be #objc.
var appId: String? {
....
}
You need to use #keyPath syntax, \ notation is not supported yet for extensions.
#keyPath(YourClass.appId)
The best solution is Here
From given link
import Foundation
extension NSObject {
//
// Retrieves an array of property names found on the current object
// using Objective-C runtime functions for introspection:
// https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtPropertyIntrospection.html
//
func propertyNames() -> Array<String> {
var results: Array<String> = [];
// retrieve the properties via the class_copyPropertyList function
var count: UInt32 = 0;
var myClass: AnyClass = self.classForCoder;
var properties = class_copyPropertyList(myClass, &count);
// iterate each objc_property_t struct
for var i: UInt32 = 0; i < count; i++ {
var property = properties[Int(i)];
// retrieve the property name by calling property_getName function
var cname = property_getName(property);
// covert the c string into a Swift string
var name = String.fromCString(cname);
results.append(name!);
}
// release objc_property_t structs
free(properties);
return results;
}
}