ios - Swift Singleton Init Called Twice in XCTest -

with swift, singleton initializer called twice when running xctest unit tests.

no problems objective-c, though, init() method called once, expected.

here's how build 2 test projects:

objective-c

singleton class

create empty objective-c project tests. add following bare-bones singleton:

#import "singleton.h"  @implementation singleton  + (singleton *)sharedinstance {     static singleton *sharedinstance = nil;     static dispatch_once_t oncetoken;     dispatch_once(&oncetoken, ^{         sharedinstance = [[singleton alloc] init];         // other initialisation stuff here     });     return sharedinstance; }  - (instancetype)init {     self = [super init];     if (self) {         nslog(@"%@", self);     }     return self; } @end 

appdelegate

in application delegate add call singleton this:

- (bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary *)launchoptions {     // override point customization after application launch.     [singleton sharedinstance];     return yes; } 

xctestcase

also add call singleton generated test class:

- (void)testexample {     [singleton sharedinstance];     // example of functional test case.     xctassert(yes, @"pass"); } 

results

if add breakpoint singleton's init method , run tests, breakpoint hit once, expected.

swift

now create new swift project , same thing.

singleton

create singleton, add test target target memberships

class singleton {     class var sharedinstance : singleton {         struct static {             static var oncetoken : dispatch_once_t = 0             static var instance : singleton? = nil         }         dispatch_once(&static.oncetoken) {             static.instance = singleton()         }         return static.instance!     }      init() {         nslog("\(self)")     } } 

appdelegate

func application(application: uiapplication, didfinishlaunchingwithoptions launchoptions: [nsobject: anyobject]?) -> bool {     // override point customization after application launch.     singleton.sharedinstance     return true } 

xctestcase

func testexample() {     // example of functional test case.     singleton.sharedinstance     xctassert(true, "pass") } 

results

this time, if add breakpoint singleton's init method , run tests, breakpoint hit twice, first app delegate, test case, i.e. you'll have 2 instances of singleton.

am missing anything?

since application module , tests module separated modules, when add singleton.swift file test target member, yourapp.singleton , yourapptest.singleton not same class. that's why init called twice.

instead of that, should import main module in test file:

import yourappname  func testexample() {     // example of functional test case.     singleton.sharedinstance     xctassert(true, "pass") } 

and singleton class must declared public. see swift, access modifiers , unit testing

public class singleton {     public class var sharedinstance : singleton {         struct static {             static var oncetoken : dispatch_once_t = 0             static var instance : singleton? = nil         }         dispatch_once(&static.oncetoken) {             static.instance = singleton()         }         return static.instance!     }      init() {         nslog("\(self)")     } } 

don't forget remove singleton.swift test target membership.