bug: event listener is not notified even though event should be retained

[johan-mjolner]

Bug Report

Calling a combination of addListener:, removeListener:, and notifyListeners:data:retainUntilConsumed: causes the notification to disappear

Capacitor Version

Version 1.2 but also latest version on Github as per 23/10/2019
npx cap doctor output:
💊 Capacitor Doctor 💊

Latest Dependencies:

@capacitor/cli: 1.2.1

@capacitor/core: 1.2.1

@capacitor/android: 1.2.1

@capacitor/ios: 1.2.1

Installed Dependencies:

@capacitor/cli 1.2.0

@capacitor/core 1.2.0

@capacitor/android 1.2.0

@capacitor/ios 1.2.0

[success] Android looking great! 👌
Found 2 Capacitor plugins for ios:
cordova-plugin-advanced-http (2.2.0)
cordova-plugin-file (6.0.2)
[success] iOS looking great! 👌

Affected Platform(s)

• Android
• iOS
• Electron
• Web

Current Behavior

I have created my own CAPPlugin subclass, where I call:

        self.notifyListeners("event", data: data, retainUntilConsumed: true)

At some point after this, my typescript files starts listening for "event":

        eventListener = Plugins.MyPlugin.addListener("event", ...)
        //...
        eventListener.remove()

This works the first time, I do this. But when repeating the same flow later, the listener is never called

Expected Behavior

I expect the listener to be called when I add the listener

Reproduction Steps

See "Current Behavior"

Resolution

The reason for the error is in CAPPlugin.m, the method "notifyListeners:data:retainUntilConsumed:". Here, there is a check for "listenersForEvent==nil". The problem is, that after adding and removing a listener, the "listenersForEvent" is not nill, but an empty array.

Please apply this pull request / this patch to fix the problem:

diff --git a/ios/Capacitor/Capacitor/CAPPlugin.m b/ios/Capacitor/Capacitor/CAPPlugin.m
index e3e1d202..5ec22f61 100644
--- a/ios/Capacitor/Capacitor/CAPPlugin.m
+++ b/ios/Capacitor/Capacitor/CAPPlugin.m
@@ -93,7 +93,7 @@ - (void)notifyListeners:(NSString *)eventName data:(NSDictionary<NSString *,id>

 - (void)notifyListeners:(NSString *)eventName data:(NSDictionary<NSString *,id> *)data retainUntilConsumed:(BOOL)retain {
   NSArray<CAPPluginCall *> *listenersForEvent = [self.eventListeners objectForKey:eventName];
-  if(listenersForEvent == nil) {
+  if(listenersForEvent == nil || [listenersForEvent count] == 0) {
     if (retain == YES) {
       [self.retainedEventArguments setObject:data forKey:eventName];
     }

[johan-mjolner]

I created a pull request for this: #2095

[jcesarmobile]

closed on #2095

[ionitron-bot]

Thanks for the issue! This issue is being locked to prevent comments that are not relevant to the original issue. If this is still an issue with the latest version of Capacitor, please create a new issue and ensure the template is fully filled out.