How do I check if a string contains another string in Swift?

Question

In Objective-C the code to check for a substring in an NSString is:

NSString *string = @\"hello Swift\";
NSRange textRange =[strin         


        

Answer 1

string.containsString is only available in 10.10 Yosemite (and probably iOS8). Also bridging it to ObjectiveC crashes in 10.9. You're trying to pass a NSString to NSCFString. I don't know the difference, but I can say 10.9 barfs when it executes this code in a OS X 10.9 app.

Here are the differences in Swift with 10.9 and 10.10: https://developer.apple.com/library/prerelease/mac/documentation/General/Reference/APIDiffsMacOSX10_10SeedDiff/index.html containsString is only available in 10.10

Range of String above works great on 10.9. I am finding developing on 10.9 is super stable with Xcode beta2. I don't use playgrounds through or the command line version of playgrounds. I'm finding if the proper frameworks are imported the autocomplete is very helpful.

Answer 2

You don't need to write any custom code for this. Starting from the 1.2 version Swift has already had all the methods you need:

• getting string length: count(string);
• checking if string contains substring: contains(string, substring);
• checking if string starts with substring: startsWith(string, substring)
• and etc.

Answer 3

Another one. Supports case and diacritic options.

Swift 3.0

struct MyString {
  static func contains(_ text: String, substring: String,
                       ignoreCase: Bool = true,
                       ignoreDiacritic: Bool = true) -> Bool {

    var options = NSString.CompareOptions()

    if ignoreCase { _ = options.insert(NSString.CompareOptions.caseInsensitive) }
    if ignoreDiacritic { _ = options.insert(NSString.CompareOptions.diacriticInsensitive) }

    return text.range(of: substring, options: options) != nil
  }
}

Usage

MyString.contains("Niels Bohr", substring: "Bohr") // true

iOS 9+

Case and diacritic insensitive function available since iOS 9.

if #available(iOS 9.0, *) {
  "Für Elise".localizedStandardContains("fur") // true
}

Answer 4

If you want to check that one String contains another Sub-String within it or not you can check it like this too,

var name = String()  
name = "John has two apples." 

Now, in this particular string if you want to know if it contains fruit name 'apple' or not you can do,

if name.contains("apple")      
{  
print("Yes , it contains fruit name")    
}    
else      
{    
 print(it does not contain any fruit name)    
}    

Hope this works for you.

Answer 5

Swift 3: Here you can see my smart search extension fro string that let you make a search on string for seeing if it contains, or maybe to filter a collection based on a search text.

https://github.com/magonicolas/Swift-Smart-String-Search

Answer 6

I've found a couple of interesting use cases. These variants make use of the rangeOfString method and I include the equality example to show how one might best use the search and comparison features of Strings in Swift 2.0

//In viewDidLoad() I assign the current object description (A Swift String) to self.loadedObjectDescription
self.loadedObjectDescription = self.myObject!.description

Later after I've made changes to self.myObject, I can refer to the following string comparison routines (setup as lazy variables that return a Bool). This allows one to check the state at any time.

lazy var objectHasChanges : Bool = {
        guard self.myObject != nil else { return false }
        return !(self.loadedObjectDescription == self.myObject!.description)
    }()

A variant of this happens when sometimes I need to analyze a missing property on that object. A string search allows me to find a particular substring being set to nil (the default when an object is created).

    lazy var isMissingProperty : Bool = {
        guard self.myObject != nil else { return true }
        let emptyPropertyValue = "myProperty = nil"
        return (self.myObject!.description.rangeOfString(emptyPropertyValue) != nil) ? true : false
    }()