How to Programmatically Determine If My App Is Running in the iPhone Simulator

How can I programmatically determine if my app is running in the iphone simulator?

Already asked, but with a very different title.

What #defines are set up by Xcode when compiling for iPhone

I'll repeat my answer from there:

It's in the SDK docs under "Compiling source code conditionally"

The relevant definition is TARGET_OS_SIMULATOR, which is defined in /usr/include/TargetConditionals.h within the iOS framework. On earlier versions of the toolchain, you had to write:

#include "TargetConditionals.h"

but this is no longer necessary on the current (Xcode 6/iOS8) toolchain.

So, for example, if you want to check that you are running on device, you should do

#if TARGET_OS_SIMULATOR
    // Simulator-specific code
#else
    // Device-specific code
#endif

depending on which is appropriate for your use-case.

How to detect if app is being built for device or simulator in Swift

Update 30/01/19

While this answer may work, the recommended solution for a static check (as clarified by several Apple engineers) is to define a custom compiler flag targeting iOS Simulators. For detailed instructions on how to do to it, see @mbelsky's answer.

Original answer

If you need a static check (e.g. not a runtime if/else) you can't detect the simulator directly, but you can detect iOS on a desktop architecture like follows

#if (arch(i386) || arch(x86_64)) && os(iOS)
    ...
#endif

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After Swift 4.1 version

Latest use, now directly for all in one condition for all types of simulators need to apply only one condition -

#if targetEnvironment(simulator)
  // your simulator code
#else
  // your real device code
#endif

For more clarification, you can check Swift proposal SE-0190

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For older version -

Clearly, this is false on a device, but it returns true for the iOS Simulator, as specified in the documentation:

The arch(i386) build configuration returns true when the code is compiled for the 32–bit iOS simulator.

If you are developing for a simulator other than iOS, you can simply vary the os parameter: e.g.

Detect the watchOS simulator

#if (arch(i386) || arch(x86_64)) && os(watchOS)
...
#endif

Detect the tvOS simulator

#if (arch(i386) || arch(x86_64)) && os(tvOS)
...
#endif

Or, even, detect any simulator

#if (arch(i386) || arch(x86_64)) && (os(iOS) || os(watchOS) || os(tvOS))
...
#endif

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If you instead are ok with a runtime check, you can inspect the TARGET_OS_SIMULATOR variable (or TARGET_IPHONE_SIMULATOR in iOS 8 and below), which is truthy on a simulator.

Please notice that this is different and slightly more limited than using a preprocessor flag. For instance you won't be able to use it in place where a if/else is syntactically invalid (e.g. outside of functions scopes).

Say, for example, that you want to have different imports on the device and on the simulator. This is impossible with a dynamic check, whereas it's trivial with a static check.

#if (arch(i386) || arch(x86_64)) && os(iOS)
  import Foo
#else
  import Bar
#endif

Also, since the flag is replaced with a 0 or a 1 by the swift preprocessor, if you directly use it in a if/else expression the compiler will raise a warning about unreachable code.

In order to work around this warning, see one of the other answers.

How to detect app is running on simulator or device

Keep in mind UIDevice provides you already with information about the device itself.

[[UIDevice currentDevice] model]

You can also use the following:

TARGET_IPHONE_SIMULATOR tells you if you're in the iPhone simulator.

TARGET_OS_IPHONE tells you that you're working on the iPhone instead of MacOS.

#if TARGET_IPHONE_SIMULATOR

    NSLog(@"Running in Simulator - no app store or giro");

#else

    NSLog(@"Running on the Device");

#endif

and when ONLY interested in the device

#if !(TARGET_IPHONE_SIMULATOR)

    NSLog(@"Running on device");

#endif

Programmatically detect if app is being run on device or simulator

#if TARGET_OS_SIMULATOR

//Simulator

#else

// Device

#endif

Pls refer this previous SO question also What #defines are set up by Xcode when compiling for iPhone

iPhone simulator - how to detect when app is running on simulator (so can setup test data)?

I obviously do use something like this ...

#import 

#if TARGET_IPHONE_SIMULATOR

// Simulator specific code

#else // TARGET_IPHONE_SIMULATOR

// Device specific code

#endif // TARGET_IPHONE_SIMULATOR

And to your second question ... Something like this should help you. In your app delegate:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  if ( ! [[NSUserDefaults standardUserDefaults] boolForKey:@"initialized"] ) {
    // Setup stuff
    [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"initialized"];
  }

  ... your code ...
}

Is there a way to tell if my code is running in Apple Watch Simulator or on a real watch

I just tried this in watchKit.

    NSString *modelNameStr = [[WKInterfaceDevice currentDevice] name];
    NSLog(@"modelNameStr: %@ ...", modelNameStr);

    if ([modelNameStr isEqualToString:@"MacBookPro2012"]) {
        //device is simulator
    }
    else
    {
        //its a real watch?
    }

2016-01-25 22:32:12.540 Watch Extension[4275:131894] awakeWithContext ...
2016-01-25 22:32:12.541 Watch Extension[4275:131894] willActivate ...
2016-01-25 22:32:12.595 Watch Extension[4275:131894] modelNameStr: MacBookPro2012 ...

Where is my code when running under IOS simulator?

Applications are installed here:

/Users//Library/Application Support/iPhone Simulator//Applications

Test my app using iPhone X simulator

The latest version of Xcode 9 GM (available from https://developer.apple.com/download/ if you have an apple developer account) contains a simulator for iPhone X

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