Contents

init(unsafeUninitializedCapacity:initializingWith:)

Creates an array with the specified capacity, and then calls the given closure with a buffer covering the array’s uninitialized memory.

Declaration

init<E>(unsafeUninitializedCapacity: Int, initializingWith initializer: (inout UnsafeMutableBufferPointer<Element>, inout Int) throws(E) -> Void) throws(E) where E : Error

Parameters

  • unsafeUninitializedCapacity:

    The number of elements to allocate space for in the new array.

  • initializer:

    A closure that initializes elements and sets the count of the new array.

    • Parameters:

      • buffer: A buffer covering uninitialized memory with room for the specified number of elements.

      • initializedCount: The count of initialized elements in the array, which begins as zero. Set initializedCount to the number of elements you initialize.

Discussion

Inside the closure, set the initializedCount parameter to the number of elements that are initialized by the closure. The memory in the range buffer[0..<initializedCount] must be initialized at the end of the closure’s execution, and the memory in the range buffer[initializedCount...] must be uninitialized. This postcondition must hold even if the initializer closure throws an error.