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Add a variable to a class instance at runtime: Difference between revisions

Add a variable to a class instance at runtime (view source)

Revision as of 09:42, 29 December 2015

165 bytes removed ,  8 years ago
→‎{{header|Swift}}
Line 1,491:
 
<lang swift>import Foundation
 
let fooKey = UnsafeMutablePointer<Void>.alloc(1)
var fooKey: UnsafePointer<()> = nil
withUnsafePointer(&fooKey) { ptr in
fooKey = UnsafePointer<()>(ptr)
} // one way to define a unique key is a pointer variable that points to itself
 
 
class MyClass { }
let e = MyClass()
 
// set
objc_setAssociatedObject(e, fooKey, 1, objc_AssociationPolicy(.OBJC_ASSOCIATION_RETAIN))
// get
if let associatedObject = objc_getAssociatedObject(e, fooKey) {
printlnprint("associated object: \(associatedObject)")
} else {
printlnprint("no associated object")
}</lang>
 
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