Delete existing database and recreate it by EntityFramework code first for asp.net core project

1. Delete the existing database
option 1: From the Visual Studio's View->SQL Server Object Explorer, delete the existing database. Note, just delete the database file from disk is not enough, as the table is still kept in system table list.
option 2: from command line, run
dotnet ef database drop

2. Delete all files from asp.net project's Migrations folder

3. From command line, run the below command to add the migration cs script to the asp.net core project
dotnet ef migrations add initial

4.Create the database and table
option 1:  From the command line, run the below command to
dotnet ef database update

option 2: call Database.Migration method from cs code when starting app. This option is particular useful for Azure deployment with connection settings as command line is not a good option for Azure cloud deployment.
public class Program
    {
        public static void Main(string[] args)
        {
            var host = CreateWebHostBuilder(args).Build();
            
            using (var scope = host.Services.CreateScope()){
                var context = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
                context.Database.Migrate();
            }
            host.Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>();
    }
}

iOS: set different row height for different prototype cells in a single table view

Since IOS 8.1,  supporting different height for different row prototype is quite easy.

First in storyboard, setting height constraint for different row prototype, then adding those rows into a single UITableView will show the height constraints are ignored at runtime and the row height is always using the row height configured in TableView row height property.

In order to apply the row height constraint defined in row prototype, add the below code in the viewController's viewDidLoad method

        tableView.estimatedRowHeight = 44

        tableView.rowHeight = UITableViewAutomaticDimension

The estimatedRowHeight can be set to the same value as configured in tableview's row height property.

Note, inside the cell, the vertical constraint must set to require the vertical cell height. For example, if a button has top and bottom and height constraints added as the cell height, it will work. But if the button only has top and height constraints, then it will not work, as the cell will be shrunked to estimated row height.

Fix "could not resolve project cordovaLib" error after upgrading to android studio 3.0.1

After upgrading to Android studio 3.0.1, when building cordova project, if error happens for

Unable to resolve dependency for ':@debug/compileClasspath': Could not resolve project :CordovaLib. Open File Show Details

Then it can be fixed by updating the android module's build.gradle with the below change:

dependencies {
    compile fileTree(dir: 'libs', include: '*.jar')
    // SUB-PROJECT DEPENDENCIES START    debugCompile(project(path: "CordovaLib", configuration: "debug"))
    releaseCompile(project(path: "CordovaLib", configuration: "release"))

    compile project(':CordovaLib')
    // SUB-PROJECT DEPENDENCIES END

} 

Mac change folder owner for permission to update file

When upgrading to High Sierra on the mac, somehow the owner needs to be updated due to an IT requirement.

After the ownership change, a lot of files are locked due to the current user does not own the file.

Updating the owner of the file and folder from Get Info page does not work as expected. So the best way to fix the issue is running chown from terminal as

sudo chown -Rv i826633 FolderPathToChangeTheOwner 

iOS 11 UIBarButtonItem may not work on real device

One iOS project has a view controller containing a table view and a toolbar, the toolbar has a UIBarButtonItem to open another view controller.

After upgrading an old ios project with XCode 9.1 and swift 4, running it on iOS 11 real device shows clicking on the UIBarButtonItem does not work as expected. However when running on iOS 11 simulator, clicking on the button works fine.

Even if after reverting all the change made during the upgrading in the project, the issue still happens, so it indicates the issue is caused by rebuilding the project using the ios 11 SDK and running it on ios 11 device.

The more investigation indicates the issue is caused by a tap gesture recognizer added in the viewcontroller's view object. The tap gesture is used for dismissing the keyboard.

In ios build prior to iOS 11, even if adding a tap gesture recognize on the view controller's view object, the toolbar button's handle will still be called. However, in iOS 11 sdk, when clicking the button, only the tap gesture recognizer's handler will be called, the button item's click handler will not be called.

The fix is quite simple, instead of adding the gesture recognizer to the view controller's view object, just add it to the tableview' view object. So that when clicking on the bar button item, it will not trigger the tap gesture recognizer's event handler

Original code:

let tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(TravelDateViewController.handleTap(recognizer:)))

self.view.addGestureRecognizer(tap)

After the fix:

let tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(TravelDateViewController.handleTap(recognizer:)))

self.tableView.addGestureRecognizer(tap)

Missing Firebase module error when adding unit test target into existing ios project

An ios xcode swift project was created a while ago with swift 3.0. Later when adding a unit test target into the project, a build error happens due to import module gets unknown module or missing Firebase module error.

For the unknown module error, it is because the module name has been changed after the project was created, the import statement requires module name instead of target name. So fix this error, just go to application's build settings' module name field and use the module name for the import statement.

The second error is due to swift version mismatch, the application target uses swift 3.0, while the new unit test target uses swift 4.0, and the Firebase library downloaded by pod file can only have one version, so both target must have the same version. From the target's Build Settings, change the swift language version to 3.0

The pod file was generated only have the configuration for application target, after adding the unit test target, it needs to be updated to also have Firebase library for unit test target as below, and then run "pod update" to update the pod

source 'https://github.com/CocoaPods/Specs.git'

platform :ios, '9.0'

target 'myapp' do

  use_frameworks!

  pod 'Firebase/Core'

  pod 'Firebase/AdMob'

  

  target 'UnitTests' do

        use_frameworks!

        inherit! :search_paths

        pod 'Firebase'

  end

end

Finally after import the application module into the test file, be sure @testable is used, so the internal class can be used by the unit test methods.

import XCTest

@testable import myapp

Avoid main thread check warning in iOS project when firebase is used

When starting ios project which integrated with Google Firebase library, the app may generate few main thread check warning as below

Main Thread Checker: UI API called on a background thread: -[UIApplication delegate]
PID: 740, TID: 51958, Thread name: (none), Queue name: FIRAnalyticsQueue, QoS: 9
Backtrace:

In addition, the ios unit test target may not be able to run at all if the main thread warning exists.

The reason is the old Google Firebase library 4.0.0 and below has not been updated for the new ios 11 and xcode 9, the issue can be fixed by updating the Google Firebase library through the pod file by running the below command from ios project root folder in mac terminal:

pod update

Currently it will update the Google Firebase library to

Installing Firebase 4.5.0 (was 4.0.0)

Installing FirebaseAnalytics 4.0.4 (was 4.0.0)

Installing FirebaseCore 4.0.10 (was 4.0.0)

Installing FirebaseInstanceID 2.0.5 (was 2.0.0)

Installing Google-Mobile-Ads-SDK 7.25.0 (was 7.20.0)

Installing GoogleToolboxForMac 2.1.3 (was 2.1.1)

Installing nanopb (0.3.8)