Swift uses InputMethodKit to write an input method

How to write an input method on iOS? This question has been answered a lot of people over。You can easily find a detailed tutorial by Google。but，On macOS write an input method is not so simple。

Ok，Strictly speaking，I mean use Swift to write a input method is difficult on macOS。The main reason is that no one has ever done this thing 。

Current data can be acquired，In addition to Apple's official API description (of no use)，And the official demo (very detailed but outdated，But also written with OC。) Outside，Almost nothing。

Now I'm writing this article is to summarize，If you want to use Swift 3 to start to write a macOS input method，What you need to bypass pit。

Info.plist

For the input method for，Need to do some additional configuration in this document which，Most of the configuration you only need to compare apples to the official launch of the Demo - theymostThey are correct。

Where there is no explanation of that point，your Bundle identifier Need to follow a certain format to write - that，This field must contain inputmethod Keyword。

For example,，That name my input LogInputMac ，So I can not write with.logcg.LogInputMac ，In this case macOS not be able to recognize it as the input method (even into the /Repository/Input Methods/ Nor)，You must inputmethod This keyword is added，And best not to put the final，It should be placed before the three dots (.) Within。For example, like me： with.logcg.inputmethod.LogInputMac 。

Other，For Swift，What you need to do a separate operation，If you like this APP will be compiled into /Repository/Input Methods/ ，So although macOS can recognize the input method，But does not actually have any effect - your IMKInputController It is not fully loaded。

This is because you can not find macOS IMKInputController class，to this end，We should InputMethodServerControllerClass and InputMethodServerDelegateClass To change the contents of the field $(PRODUCT_MODULE_NAME). Form of Prefix，That is，It should be written like this：

Use Swift working with InputMethodKit

AppDelegate.swift

Because it works with an ordinary InputMethodKit different APP，We need to start the application initialization IMKServer class，The first reaction of most people is to put it applicationDidFinishLaunching(_ : ) Go execution，On the contrary，Since there is no main function Swift，We can declare it as a global variable without the need to give a global variable assignment statement，We write it in applicationDidFinishLaunching in，At the same time you can also here to do some extra preparation.，For example, copy it thesaurus：

Print(_:)

Because Swift is not OC use NSLog to output console messages，We all still like to use Print(_:) To achieve the printing terminal content - for the input method for，You can not debug a program。

If you perform your input directly with Xcode，There is no effect。Want to test input，We must put it /Repository/Input Methods/ And then load。In that case，Even if you use Xcode attach to an input method process，You will not get any output terminal。

This time you need to use NSLog ，It can easily input message is output to the console，So you can open a console，And then view the information process。

Debug

For the input method for，In osx it is a global thing，So it is hard to debug it be，In short，We can still make the development process as much as possible comfortable，First of all，You need to change the directory permissions input method：

This allows Xcode compiled directly into the directory，then，In the editing target in Xcode，

Build Settings > All > Build Locations > Per-configuration Build Products Path > Debug

The value corresponding to： /Library/Input Methods

So you can directly compiled，Add in System Preferences once，After compiling the facts can take effect，Back and forth without a restart or logout。

It is noteworthy that：Do not add breakpoints ......

Further reading

At last，Put hereThe only oneI could find the ChinesePresentation of the article InputMethodKit，We can refer to (unfortunately，I did not use this article，Because to find it when I have stepped on all the above pit)。

half year later，I restarted the project，And we found another one very useful article：IMK input method based on (a) the macOS - creating step

Other，I thought you might still unable to successfully control OC code to convert Swift project，So I put the Apple official correspondence "NumberInput_IMKit_Sample-NumberInput_0" the Swift project package upload，If desired, you canDownload Resources。

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