Dai Dai - 4 months ago 59
Swift Question

Settings bundle values returning nil

I added a Settings bundle to my app and in Xcode it appears in the root of my project tree view.

The

Root.plist
file looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>StringsTable</key>
<string>Root</string>
<key>PreferenceSpecifiers</key>
<array>
<dict>
<key>Type</key>
<string>PSGroupSpecifier</string>
<key>Title</key>
<string>Service</string>
</dict>
<dict>
<key>Type</key>
<string>PSTextFieldSpecifier</string>
<key>Title</key>
<string>Hostname</string>
<key>Key</key>
<string>service_hostname</string>
<!-- and so on -->


When I open the Settings app on iOS the entry appears at the bottom and I can display and edit my settings perfectly fine.

However I cannot retrieve these values from code. Here's my code:

static func loadSettings() {

let ud = NSUserDefaults.standardUserDefaults()
ud.synchronize()

Settings.hostName = ud.stringForKey("service_hostname")
// etc
}


I also tried
ud.objectForKey
and
ud.valueForKey
- both return
nil
as well.

After setting
Settings.hostName
the Xcode debugger reports it has a value of
nil
despite me setting an explicit value in the Settings app.

I saw this thread ( iPhone App : How to get default value from root.plist? ) where someone posted a chunk of Objective-C code that manually loads the
Root.plist
file directly into an
NSMutableDictionary
and calls
NSUserDefaults.standardUserDefaults().registerDefaults
but that seems like a hack (and I can't get it to work in Swift because the compiler says that
stringByAppendingPathComponent
doesn't exist anymore)

Why isn't
NSUserDefaults
picking up the settings from the Settings app?

Dai Dai
Answer

Apparently the cause is that if my settings in the plist have defaults defined and the user has not explicitly set a value, then the value displayed in the Settings app will be the defaults from the plist file, however the NSUserDefaults API will still return nil.

Unfortunately this means that if the default value is meaningful (such as a default web-service address URI: "http://www.example.com") it must exist twice in my project: as a default in the plist and in my program code:

Root.plist:

  <dict>
      <key>Key</key>          <string>mySettingKey</string>
      <key>Title</key>        <string>Some address</string>
      <key>Type</key>         <string>PSTextFieldSpecifier</string>
      <key>DefaultValue</key> <string>http://www.example.com</string>
      <key>IsSecure</key>     <false />
      <key>KeyboardType</key> <string>Alphabet</string>
  </dict>

Program.swift:

let ud = NSUserDefaults.standardUserDefaults()
ud.synchronize()

var mySettingValue = ud.stringForKey("mySettingKey")
if mySettingValue == nil {
    mySettingValue = "http://www.example.com"
}

That's surprising.