Apple Mail.app Plugin Development

I used to receive an emails about How to: Apple Mail.app plugin development? then responded with enough details to begin their journey. Then I thought create an article around Apple Mail.app plugin development for community.

I believe this article would provide guidance for your plugin development. Have queries use Disqus thread at the end of article.

Attention: Apple doesn’t support officially plugin development for Mail.app. Hence no documentation & support around it. Okay let’s say the word ‘No warranties :)’

If I get an enough time, will do article for –

Custom menu & menu commands into the Mail.app
Utilizing Mail.app preferences file, so migration/upgrade is easy for users
Custom preferences panel & preferences file
Custom window

Steps to create a Mail.app plugin

Note: Following steps using Xcode 5.1.1, could be used with other version too. Ensure values are placed in appropriate places.

Step 1

Create a Xcode project type ‘Bundle‘ and Click ‘Next‘

Enter Product Name
- For example: SampleMailPlugin
Enter Company Identifier
- For example: com.myjeeva
Click Next
Save dialog appears, save SampleMailPlugin Xcode project to hard drive

Step 2

Select a Project in the navigator, target is selected by default

Fill up following Key value as per need (All the values here goes to Info.plist)
- Bundle name
- Bundle identifier
- Bundle version
Enter Class Prefix under ‘Project Document‘ Section
- For example: SMP

Step 3

Select a Project

Go to ‘Info‘ Tab and pick OS X Deployment Target
Go to Build Settings Tab
- Select ‘Base SDK‘ per choice
- set ‘Debug Information format‘ value to DWARF
- set ‘Installation Directory‘ value to $(HOME)/Library/Mail/Bundles
- set ‘Info.plist‘ value to SampleMailPlugin-Info.plist
- set ‘ProductName‘ value to SampleMailPlugin

Step 4

Select ‘SampleMailPlugin‘ group on Project Navigator

Create a Objective-C class
- For example: create SampleMailPlugin class, prefix is pre-populated
Now SMPSampleMailPlugin.h & SMPSampleMailPlugin.m gets created

Step 5

Select project root ‘SampleMailPlugin‘ on the Project Navigator

Select ‘SampleMailPlugin‘ target from popup menu
Go to Info Tab (All the values here goes to Info.plist)
- Add a Key Principle class and choose type as String enter value as ‘SMPSampleMailPlugin‘. This is entrypoint for mailbundle
- Add a Key SupportedPluginCompatibilityUUIDs and choose type as Array
  - Fill Mail.app UUID (mail version is 7.3) – D1EFE124-86FF-4751-BF00-80B2C0D6F2E4
  - Get your Mail.app UUID, use for development; this command might help you defaults read /Applications/Mail.app/Contents/Info PluginCompatibilityUUID
Go to ‘Build Settings‘ Tab
- set ‘Installation Directory‘ value to $(HOME)/Library/Mail/Bundles
- set ‘Wrapper Extension‘ value to mailbundle
Go to ‘Build Phases‘ Tab
- Add new ‘Build Phase‘ of type Copy Files
- Double click ‘Copy Files‘ label and Update the heading to Local Deploy
- Select ‘Destination‘ value as Absolute Path
- set ‘Path‘ value to ~/Library/Mail/Bundles. It deploys the current build into mentioned local path
- Click on ‘Plus‘ sign button then choose SampleMailPlugin.mailbundle or just drag a SampleMailPlugin.mailbundle form Project Navigator to here

Step 6

Select SMPSampleMailPlugin.m file on the Project Navigator

Create a class method called + (void)initialize { .... }
Add following Code Snippet into method initialize

Class mvMailBundleClass = NSClassFromString(@"MVMailBundle");

// If this class is not available that means Mail.app
// doesn't allow bundles anymore. Fingers crossed that this never happens!
if (!mvMailBundleClass) {
	NSLog(@"Mail.app doesn't support bundles anymore, So deadlock !");
	return;
} 

// Registering plugin in Mail.app
[mvMailBundleClass registerBundle];

NSLog(@"SampleMailPlugin successfully Loaded");

Class mvMailBundleClass = NSClassFromString(@"MVMailBundle");

// If this class is not available that means Mail.app

// doesn't allow bundles anymore. Fingers crossed that this never happens!

if (!mvMailBundleClass) {

NSLog(@"Mail.app doesn't support bundles anymore, So deadlock !");

return;

}

// Registering plugin in Mail.app

[mvMailBundleClass registerBundle];

NSLog(@"SampleMailPlugin successfully Loaded");

Add following interface definition into SMPSampleMailPlugin.m

@interface SMPSampleMailPlugin (SMPNoImplementation)

+ (void)registerBundle;

@end

@interface SMPSampleMailPlugin (SMPNoImplementation)

+ (void)registerBundle;

@end

Step 7

Let’s build the plugin and test. Press Command + B or go to Product menu click Build.

Step 8

Look at our new build mail plugin and Console.app

Open up Finder hold Command + Shift key and press G
Type ~/Library/Mail/Bundles hit the ‘Go‘ button, now SampleMailPlugin.mailbundle should be there
Open up Console.app
Type ‘Mail‘ in right upper Search text box in Console.app to limit message to Mail.app

Step 9

Final goal, open up Mail.app. Now you should similar message in console.app

8/29/14 1:27:05.656 PM Mail[42713]: SampleMailPlugin successfully Loaded

1	8/29/14 1:27:05.656 PM Mail[42713]: SampleMailPlugin successfully Loaded

Step 10 (Optional)

If you’re using or developing Mail.app plugin for a first time; Plugin support may not be enabled in Mail.app, so execute below command in the Terminal.app. Restart the Mail.app

$ defaults write com.apple.mail EnableBundles -bool true

1	$ defaults write com.apple.mail EnableBundles -bool true

I believe you’re Happy, spread the word of ReplyWithHeader Mail plugin and give some star on MacUpdate.com and GitHub.com 🙂

Download

If you have any queries, please leave a comment below!

SampleMailPlugin Archive