Bug 38478 - Custom autocomplete only operates correctly when debugger attached
Summary: Custom autocomplete only operates correctly when debugger attached
Alias: None
Product: iOS
Classification: Xamarin
Component: Debugger ()
Version: XI 9.4 (iOS 9.2)
Hardware: PC Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Rolf Bjarne Kvinge [MSFT]
Depends on:
Reported: 2016-02-05 02:47 UTC by Cody Beyer (MSFT)
Modified: 2016-02-05 13:39 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

Sample (17.21 KB, application/zip)
2016-02-05 02:47 UTC, Cody Beyer (MSFT)

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Description Cody Beyer (MSFT) 2016-02-05 02:47:19 UTC
Created attachment 14904 [details]

# Description

The following app implements autocomplete using a tableview and responding to entries to a text field. When the debugger is attached, this operation works as expected. When the debugger is not attached, the list does not refresh as expected.

# Sample


# Video


# Steps to Reproduce

1. Download sample
2. Deploy to iOS Device
3. Ensure debugger is not attached
4. Type R into box
5. Notice list as autocomplete options
6. Type e

# Expected Results

Purple should no longer display

# Actual Results

Purple is still displayed

# Versions

=== Xamarin Studio ===

Version 5.10.2 (build 56)
Installation UUID: 03fd4312-a495-46bf-b10d-1df680f5b853
	Mono 4.2.2 (explicit/996df3c)
	GTK+ 2.24.23 (Raleigh theme)

	Package version: 402020030

=== Xamarin.Profiler ===

Not Installed

=== Xamarin.Android ===

Version: (Business Edition)
Android SDK: /Users/codybeyer/Library/Developer/Xamarin/android-sdk-macosx
	Supported Android versions:
		4.0.3 (API level 15)
		4.4   (API level 19)
		6.0   (API level 23)

SDK Tools Version: 24.4.1
SDK Platform Tools Version: 23.1.0
SDK Build Tools Version: 23.0.2

Java SDK: /usr
java version "1.7.0_71"
Java(TM) SE Runtime Environment (build 1.7.0_71-b14)
Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode)

=== Xamarin Android Player ===

Version: 0.6.5
Location: /Applications/Xamarin Android Player.app

=== Apple Developer Tools ===

Xcode 7.2.1 (9548.1)
Build 7C1002

=== Xamarin.iOS ===

Version: (Business Edition)
Hash: 962a050
Branch: master
Build date: 2016-01-29 16:59:11-0500

=== Xamarin.Mac ===

Version: (Business Edition)

=== Build Information ===

Release ID: 510020056
Git revision: bb74ff467c62ded42b7b7ac7fdd2edc60f8647b0
Build date: 2016-01-26 16:24:41-05
Xamarin addins: 8b797d7ba24d5abab226c2cf9fda77f666263f1b
Build lane: monodevelop-lion-cycle6-c6sr1

=== Operating System ===

Mac OS X 10.11.3
Darwin Codys-Mac.local 15.3.0 Darwin Kernel Version 15.3.0
	Thu Dec 10 18:40:58 PST 2015
	root:xnu-3248.30.4~1/RELEASE_X86_64 x86_64
Comment 1 Rolf Bjarne Kvinge [MSFT] 2016-02-05 13:39:34 UTC
This works if you introduce a delay in the UpdateSuggestions method:

	public void UpdateSuggestions ()
		Thread.Sleep (250);
		// ...

that means that you have a race condition, and the reason it works when the debugger attached is that the debugger adds an overhead to thread creation that is essentially the same as the Thread.Sleep above.

The problem is that you're expecting the text field to have changed immediately after ShouldChangeCharacters returns, but that's not the case, it does not happen immediately (you can create a thread, run code on that thread, and post a callback to the main thread before the text field is updated).

You must instead observe the TextDidChange notification:

	UITextField.Notifications.ObserveTextFieldTextDidChange ((sender, args) => {
		var autoCompleteThread = new Thread(UpdateSuggestions);