Reading values from any plist file or bundle in Swift

It is super convenient to keep your settings or default values in a .plist file for your project. It allows you to keep your code the same across various apps while differences only residing in a configuration file. It becomes more sophisticated when you create a Settings.bundle and store your preferences there. This makes it easy to distribute settings across multiple apps.

This is all nice and dandy until you actually need to read values out of the .plist or bundle. Take the below example of a .plist file containing values you would like available for your app:

To extract these values into a `[String: AnyObject]`, you’ll have to call some awkward API’s from Apple. For convenience, below you’ll find an extension I created off the NSBundle class so you can easily get those values from any .plist file or bundle:

public extension NSBundle {
    
    /**
     Gets the contents of the specified plist file.
     
     - parameter plistName: property list where defaults are declared
     - parameter bundle: bundle where defaults reside
     
     - returns: dictionary of values
     */
    public static func contentsOfFile(plistName: String, bundle: NSBundle? = nil) -> [String : AnyObject] {
        let fileParts = plistName.componentsSeparatedByString(".")
        
        guard fileParts.count == 2,
            let resourcePath = (bundle ?? NSBundle.mainBundle()).pathForResource(fileParts[0], ofType: fileParts[1]),
            let contents = NSDictionary(contentsOfFile: resourcePath) as? [String : AnyObject]
            else { return [:] }
        
        return contents
    }
    
    /**
     Gets the contents of the specified bundle URL.
     
     - parameter bundleURL: bundle URL where defaults reside
     - parameter plistName: property list where defaults are declared
     
     - returns: dictionary of values
     */
    public static func contentsOfFile(bundleURL bundleURL: NSURL, plistName: String = "Root.plist") -> [String : AnyObject] {
        // Extract plist file from bundle
        guard let contents = NSDictionary(contentsOfURL: bundleURL.URLByAppendingPathComponent(plistName))
            else { return [:] }
        
        // Collect default values
        guard let preferences = contents.valueForKey("PreferenceSpecifiers") as? [String: AnyObject]
            else { return [:] }
        
        return preferences
    }
    
    /**
     Gets the contents of the specified bundle name.
     
     - parameter bundleName: bundle name where defaults reside
     - parameter plistName: property list where defaults are declared
     
     - returns: dictionary of values
     */
    public static func contentsOfFile(bundleName bundleName: String, plistName: String = "Root.plist") -> [String : AnyObject] {
        guard let bundleURL = NSBundle.mainBundle().URLForResource(bundleName, withExtension: "bundle")
            else { return [:] }
        
        return contentsOfFile(bundleURL: bundleURL, plistName: plistName)
    }
    
    /**
     Gets the contents of the specified bundle.
     
     - parameter bundle: bundle where defaults reside
     - parameter bundleName: bundle name where defaults reside
     - parameter plistName: property list where defaults are declared
     
     - returns: dictionary of values
     */
    public static func contentsOfFile(bundle bundle: NSBundle, bundleName: String = "Settings", plistName: String = "Root.plist") -> [String : AnyObject] {
        guard let bundleURL = bundle.URLForResource(bundleName, withExtension: "bundle")
            else { return [:] }
        
        return contentsOfFile(bundleURL: bundleURL, plistName: plistName)
    }
    
}

I provided several overloaded functions to read from any .plist file or bundle. Note that if you would like to use a Settings.bundle, open up the “Root.plist” file, then right-click in the contents pane, go to “Property List Type”, and select “Info.plist”. This will allow to add a dictionary of values into the “Root.plist” file.

Now with the above extension in place, you can simply use it like this:

let values = NSBundle.contentsOfFile("Settings.plist")
print(values["MyString1"]) // My string value 1.

The dictionary in the previous screenshot was displaying values from a file called “Settings.plist”. The above code snippet retrieves those values and puts them into a dictionary in one line with all the safe guards in place. Enjoy 🙂

HAPPY CODING!!