Using Predicate in Swift

Question

I m working through the tutorial here  learning Swift  for my first app  http   www appcoda com search-bar-tutorial-ios7   I m stuck on this part  Objective-C code    -  void filterContentForSearchText  NSString  searchText scope  NSString  scope       NSPredicate  resultPredicate    NSPredicate predicateWithFormat   name contains c               searchText       searchResults    recipes filteredArrayUsingPredicate resultPredicate       Can anyone advise how to create an equivalent for NSPredicate in Swift

User · Answer

You can use filters available in swift to filter content from an array instead of using a predicate like in Objective-C.

An example in Swift 4.0 is as follows:

var stringArray = ["foundation","coredata","coregraphics"]
stringArray = stringArray.filter { $0.contains("core") }

In the above example, since each element in the array is a string you can use the contains method to filter the array.

If the array contains custom objects, then the properties of that object can be used to filter the elements similarly.

User · Answer

This is really just a syntax switch  OK  so we have this method call    NSPredicate predicateWithFormat   name contains c       searchText     In Swift  constructors skip the  blahWith     part and just use the class name as a function and then go straight to the arguments  so  NSPredicate predicateWithFormat       would become NSPredicate format         For another example   NSArray arrayWithObject       would become NSArray object        This is a regular pattern in Swift    So now we just need to pass the arguments to the constructor  In Objective-C  NSString literals look like      but in Swift we just use quotation marks for strings  So that gives us   let resultPredicate   NSPredicate format   name contains c       searchText    And in fact that is exactly what we need here    Incidentally  you ll notice some of the other answers instead use a format string like  name contains c    searchText    That is not correct  That uses string interpolation  which is different from predicate formatting and will generally not work for this

User · Answer

In swift 2 2  func filterContentForSearchText searchText  String  scope  String        var resultPredicate   NSPredicate format   name contains c               searchText      searchResults    recipes as NSArray  filteredArrayUsingPredicate resultPredicate      In swift 3 0    func filterContent forSearchText searchText  String  scope  String            var resultPredicate   NSPredicate format   name contains c               searchText          searchResults   recipes filtered using  resultPredicate

User · Answer

Use The Below code    func filterContentForSearchText searchText NSString  scopes scope NSString          var searchText           var resultPredicate   NSPredicate   NSPredicate format   name contains c   searchText    nil         var recipes   NSArray   NSArray        var searchResults   recipes filteredArrayUsingPredicate resultPredicate

User · Answer

Example how to use in swift 2 0  let dataSource          Domain CheckService        IMEI check        Compliant about service provider        Compliant about TRA        Enquires        Suggestion        SMS Spam        Poor Coverage        Help Salim    let searchString    Enq  let predicate   NSPredicate format   SELF contains      searchString  let searchDataSource   dataSource filter   predicate evaluateWithObject  0      You will get  playground

User · Answer

I think this would be a better way to do it in Swift   func filterContentForSearchText searchText NSString  scope NSString       searchResults   recipes filter   name rangeOfString searchText     nil

User · Answer

change  name  and  value  according to your array data      Change  yourDataArrayName  name accroding to your array NSArray        let resultPredicate   NSPredicate format   SELF name contains c        value        if let sortedDta   yourDataArrayName filtered using  resultPredicate  as  NSArray       enter code here           print sortedDta

User · Answer

Working with predicate for pretty long time  Here is my conclusion  SWIFT     Customizable   for me was just important if at least one  request fetchLimit   1     IF IS EQUAL    1 OBJECT request predicate   NSPredicate format   name        txtFieldName text     ARRAY request predicate   NSPredicate format   name      AND nickName        argumentArray   name  nickname        IF CONTAINS    1 OBJECT request predicate   NSPredicate format   name contains c       txtFieldName text     ARRAY request predicate   NSPredicate format   name contains c     AND nickName contains c       argumentArray   name  nickname

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