Posted in iOS, Swift

iOS, Swift | Button click action issue

Environment

Xcode Version 9.0.1

 

Symptom

 

Button click action makes error

unrecognized selector sent to instance

 

Resolution

Select View Controller instead of other objects as an object when connecting UIButton action

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Posted in iOS, Swift

iOS, Swift | UI connection between storyboard and .swift source issue

Environment

Xcode Version 9.0.1

 

Symptom


Error occurs whenever control-drag to connect ui and source from storyboard to .swift file like the screenshot.

Terminating app due to uncaught exception ‘NSUnknownKeyException’, reason: ‘[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key

Resolution


Try control-drag from an UI image in storyboard to a source code like the above image.

And then build and run an application.

After this, the both ways works.

1st – control-drag from a title of an UI in storyboard to a source file.

2nd – control-drag from an UI image in story board to a source file.

I don’t understand why. But it works for me.

 

Posted in Mysql

MySQL

Symptom

$ mysql -u root

ERROR 1698 (28000): Access denied for user ‘root’@’localhost’

$ /usr/bin/mysqld_safe –skip-grant &

mysqld_safe A mysqld process already exists

$ sudo killall mysqld mysqld_safe

mysqld_safe Directory ‘/var/run/mysqld’ for UNIX socket file don’t exists.

$ sudo /usr/bin/mysqld_safe –skip-grant &

mysqld_safe Directory ‘/var/run/mysqld’ for UNIX socket file don’t exists.

 

Solution

$ sudo killall mysqld mysqld_safe

$ sudo mkdir -p /var/run/mysqld

$ sudo chown mysql:mysql /var/run/mysqld

$ sudo /usr/bin/mysqld_safe –skip-grant &

$ sudo /usr/bin/mysqld_safe –skip-grant-tables &

$ mysql -u root

Posted in iOS, Swift

iOS – Swift | Screen transition with data

Key point : Call the ‘performSegue’ function in viewDidAppear section

1. Generate Segue

Control-Drag a mouse point from the circle of starting view controller to the ending view controller

2. Select ‘Present Modally’

3. Select the arrow line

4. Set the ‘Storyboard Segue – Identifier’

5. Insert the source code to the ‘viewDidAppear’ section at a swift file for the view controller.

    override func viewDidAppear(_ animated: Bool) {
        performSegue(withIdentifier: "SignupSegue", sender: self)
    }