Function

dispatchPrecondition(condition:)

Checks a dispatch condition necessary for further execution.

Declaration

func dispatchPrecondition(condition: @autoclosure () -> DispatchPredicate)

Parameters

condition

A dispatch predicate for the current context to check.

Discussion

Use this function to detect conditions about the current execution context that must prevent the program from proceeding even in shipping code.

  • In playgrounds and -Onone builds (the default for Xcode’s Debug configuration): if condition evaluates to false, stop program execution in a debuggable state.

  • In -O builds (the default for Xcode’s Release configuration): if condition evaluates to false, stop program execution.

  • In -Ounchecked builds, condition is not evaluated, but the optimizer may assume that it would evaluate to true. Failure to satisfy that assumption in -Ounchecked builds is a serious programming error.

See Also

Dispatch Objects

class DispatchObject

The base class for most dispatch types.

enum DispatchPredicate

Logical conditions to evaluate within a given execution context.