Swift Error

When I develop an iOS app, I add a UITextField in the app UI programmatically. And I also add some constraints to the UITextField object in swift source code to make it auto layout. But when I run the app, it throws an exception with the error message ‘NSGenericException’, reason: ‘Unable to activate constraint with …

How To Fix Swift Error Unable To Activate Constraint With Anchors Because They Have No Common Ancestor & LayoutConstraints Unable To Simultaneously Satisfy Constraints Read More »

When i upgrade my Xcode to version 10.3 and build my iOS project, i meet an error message like this Failed to find or create execution context for description ‘<IBCocoaTouchPlatformToolDescription: 0x7fe0cfa54080> System content for IBCocoaTouchFramework-ElevenAndLater <IBScaleFactorDeviceTypeDescription: 0x7fe0cfa63cb0> scaleFactor=2x’. These intermediate objects were non-nil:. This error confused me a lot of time. But finally i find …

How To Fix Xcode Error Failed To Find Or Create Execution Context For Description IBCocoaTouchPlatformToolDescription 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.