How to create Int32 through UnsafePointer<Int32>?

Question

I want to get a value of Int32 through an Int32 Pointer .

var result:Int32 = 32
var y = withUnsafePointer(&result, {(point:UnsafePointer<Int32>) -> UnsafePointer<Int32> in
    return point
})

Answer 1

It is like every UnsafePointer<>. Example: NSErrorPointer which is an AutoreleasingUnsafePointer<NSError?> you can get the value with the memory attribute.

Use the attribute memory

var errPtr: UnsafePointer<NSError> = ...
var err: NSError = errPtr.memory // not optional

Solution to your example is very easy then:

var result:Int32 = 32
var y = withUnsafePointer(&result, {(point:UnsafePointer<Int32>) -> UnsafePointer<Int32> in
    return point
    })
y.memory // in the playground it shows 32 :-D

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There is no dereference operator in Swift, in C it was the aterisk * , but that is not possible in Swift.

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The documentation is very helpful.

Answer 2

The type UnsafePointer<Memory> has a subscript operator. Provided that the pointer points to something, subscript 0 always exists, so this works in a playground and it has the advantage that the reference guide has the subscript documented but not the memory property.

var result:Int32 = 32
var y = withUnsafePointer(&result, {(point:UnsafePointer<Int32>) -> UnsafePointer<Int32> in
    return point
})

y[0]  // 32