I want to implement an effect that when the iOS app starts, it popup an alert dialog on the screen and displays some messages. But during the process, I meet an error message like below, and the alert dialog is not displayed as I want. This article will tell you how to fix this issue.
If you want to import objective-c class’s .h and .m file into the swift project, Xcode will create an Objective-C Bridging Header file in the swift project automatically. But sometimes you will find it does not create the objective-c bridging header file, so you need to create and configure it manually. This article will tell
How To Fix Xcode Not Automatically Creating Bridging Header File Issue Read More »
Xcode uses workspace and projects to manage swift source code. When you develop an iOS app, you should first create a workspace, and then create and add a new project into it. You can also add existing projects into the Xcode workspace. This article will tell you how to do it.
How To Create Xcode Workspace And Add New / Exist Project Into It Read More »
When we define a swift function, we can provide function parameters to it, and each function parameter can have an external name and an internal name. External name is used by the caller to pass value to the parameter, internal name is used by the function body to get the parameter value. Below is a
iOS Swift Function External And Internal Parameter Name Example Read More »
Xcode project organizes project resource files use Asset Catalog. Each asset catalog can contain multiple asset sets such as app icon set, image set, color set, etc. When you create an Xcode project use one project template such as Single View App, it will create a default asset catalog file Assets.xcassets in the project files
How To Add iOS App Icon, Image, Color Set To Xcode Project Assets Catalog Correctly Read More »
In the previous article, we have learned how to change swift constraints use the auto-layout toolbar visually ( How To Add Constraints In Xcode 10 To Implement Auto Layout ). In this article, I will show you an example of how to use class UIKit.NSLayoutConstraint, UIKit.NSLayoutAnchor and Visual Format Language to add constraints to the
How To Change Swift Constraints To Make Autolayout Programmatically Read More »
When you develop an iOS app use swift, you can make the UI components fixed size. But iOS devices have different screen sizes, so the fixed size UI components will render differently on different iOS devices. Even when you change the same iOS device’s orientation from portrait to landscape, the fixed size UI design will
How To Add Constraints In Xcode 10 To Implement Auto Layout Read More »
When you use UIKit.UIButton class’s setImage method to set swift button’s icon image, if the image is not icon format, it will display a purely blue color rectangle instead of the image. You can fix this error by converting the image to an icon format image. But you can also fix this error by setting
How To Fix Image Not Showing Error For Swift Button Read More »
Swift optional variable is a variable that can have nil ( same to null ) value. And you do not need to initialize an optional variable before using it. If not initialized, the optional variable value is nil. It does not like none optional variable which you must assign an initial value before using it.
How To Fix Swift Fatal Error: Unexpectedly Found Nil While Unwrapping An Optional Value Read More »
In the previous article ( in this article’s reference section ), we have learned how to create a swift button with UIButton class and how to add click event process function to it, we have also known how to set the swift button’s background color and how to create a different type of swift button.
How To Set Swift Button Background Image Example Read More »