Tip - Redirecting Users to the Setting Page (iOS 8)

In iOS, you often need to redirect the user to the Settings page. For example, if you detected that the user has turned off WiFi and your application needs to access the Internet using WiFi, you might want to automatically launch the Settings page so that the user can turn on the WiFi directly. In iOS 8, you can do so via the UIApplicationOpenSettingsURLString constant, like this:

        if UIApplicationOpenSettingsURLString != nil {

            var appSettings = NSURL(string: UIApplicationOpenSettingsURLString)

            UIApplication.sharedApplication().openURL(appSettings!)

        }

The above code snippet will redirect the user to the Settings page. 

Xcode 6 - iPhone Simulator Folder

In Xcode 6, the location of the applications on the iPhone Simulator has changed. Prior to iOS 8, the location of the Documents folder of your app can be found here:

/Users/weimenglee/Library/Application\ Support/iPhone\ Simulator/<iOS_Version>/Applications/<application_id>/Documents 

In xCode 6, the location of the simulator has changed to:

/Users/weimenglee/Library/Developer/CoreSimulator/

However, this location contains a list of folders for different types of simulators. If you go into this folder, you will see something like this:

Each folder correspond to a specific iPhone Simulator. To know which folder corresponds to which simulator, use the following command in Terminal:

Weis-Mac-mini:~ weimenglee$ xcrun simctl list

== Device Types ==

iPhone 4s (com.apple.CoreSimulator.SimDeviceType.iPhone-4s)

iPhone 5 (com.apple.CoreSimulator.SimDeviceType.iPhone-5)

iPhone 5s (com.apple.CoreSimulator.SimDeviceType.iPhone-5s)

iPhone 6 Plus (com.apple.CoreSimulator.SimDeviceType.iPhone-6-Plus)

iPhone 6 (com.apple.CoreSimulator.SimDeviceType.iPhone-6)

iPad 2 (com.apple.CoreSimulator.SimDeviceType.iPad-2)

iPad Retina (com.apple.CoreSimulator.SimDeviceType.iPad-Retina)

iPad Air (com.apple.CoreSimulator.SimDeviceType.iPad-Air)

Resizable iPhone (com.apple.CoreSimulator.SimDeviceType.Resizable-iPhone)

Resizable iPad (com.apple.CoreSimulator.SimDeviceType.Resizable-iPad)

== Runtimes ==

iOS 7.0 (7.0 - Unknown) (com.apple.CoreSimulator.SimRuntime.iOS-7-0) (unavailable, runtime path not found)

iOS 7.1 (7.1 - Unknown) (com.apple.CoreSimulator.SimRuntime.iOS-7-1) (unavailable, runtime path not found)

iOS 8.0 (8.0 - 12A365) (com.apple.CoreSimulator.SimRuntime.iOS-8-0)

== Devices ==

-- iOS 7.0 --

-- iOS 7.1 --

-- iOS 8.0 --

    iPhone 4s (8C1303A2-C590-4822-BB9B-12EC32035C8C) (Shutdown)

    iPhone 5 (402C822D-567F-4F3A-B113-1499C5A7949C) (Shutdown)

    iPhone 5s (B6D71F6A-E94B-47ED-AF25-882FDEF8E6F5) (Shutdown)

    iPhone 6 Plus (5BCD1507-6F06-4D66-B71D-47670EB703B2) (Shutdown)

    iPhone 6 (00100565-4E4D-4D9A-A875-544E0A6E4F4F) (Booted)

    iPad 2 (187D75DD-824D-4381-AE2F-BDF57FEB87E0) (Shutdown)

    iPad Retina (604667D3-8366-4147-B0AD-F7840198713C) (Shutdown)

    iPad Air (01D6AEBC-F12A-47EE-82CB-0140AF117AE0) (Shutdown)

    Resizable iPhone (9C138BCD-BFB9-4AEB-A218-F0F99F678220) (Shutdown)

    Resizable iPad (4966C908-AAA7-43EC-8E3A-EADF8BFA3C05) (Shutdown)

Weis-Mac-mini:~ weimenglee$ 

In my example here, I am looking for iPhone 6, which has the device id of 00100565-4E4D-4D9A-A875-544E0A6E4F4F. You can then go into this folder and the following path shows the folder that contains all the applications installed on this simulator:

/Users/weimenglee/Library/Developer/CoreSimulator/Devices/00100565-4E4D-4D9A-A875-544E0A6E4F4F/data/Containers/Data/Application/

You can now locate your specific application and find the Documents folder:

/Users/weimenglee/Library/Developer/CoreSimulator/Devices/00100565-4E4D-4D9A-A875-544E0A6E4F4F/data/Containers/Data/Application/FD7949EA-7D39-4BC6-95F4-77F320592651/Documents/

Swift - Generating a random number

If you want to generate a random number in Swift, use the arc4random_uniform() function. The following code snippet generates a number from 0 to 9:

var i = Int(arc4random_uniform(10))

iOS 8 - Getting Location Data

Getting location data in iOS 8 has changed drastically. Here is what you need to do if you are using the CLLocationManager class to get a location in iOS 8.

In iOS 8, you need to add the following two keys in your info.plist file:

For getting location in the foreground

Key

NSLocationWhenInUseUsageDescription

Value

"This app will display your current location" (up to you to write anything you want here)

For getting location in the background

Key

NSLocationAlwaysUsageDescription

Value

"This app will log your location into a database" (up to you to write anything you want here)

Before you use the startUpdatingLocation() method, you have to request for user's permission. To use the location in the foreground, call the requestWhenInUseAuthorization() method:

var lm: CLLocationManager!

...

        if (UIDevice.currentDevice().systemVersion as NSString).floatValue>=8.0 {            

            //---request for foreground location use---

            lm.requestWhenInUseAuthorization()

        }

        

        lm.startUpdatingLocation()

If you want to continue getting location data in the background, call the requestAlwaysAuthorization() method:

        if (UIDevice.currentDevice().systemVersion as NSString).floatValue>=8.0 {

            //---request for background location use---

            lm.requestAlwaysAuthorization()

        }

Note that if you want the app to access location information both in the foreground and in the background, it is sufficient to call the requestAlwaysAuthorization() method.