In Xcode 6.3 and later (including Xcode 7 and 8), console output appears in the Debug area at the bottom of the playground window (similar to where it appears in a project). To show it: Menu: View > Debug Area > Show Debug Area (⌘⇧Y) Click the middle button of the workspace-layout widget in the … Read more
You cannot initialize an instance class property referencing another instance property of the same class, because it’s not guaranteed in which order they will be initialized – and swift prohibits that, hence the (misleading) compiler error. You have to move the initialization in a constructor as follows: let components: NSDateComponents init() { self.components = myCalendar.components(.CalendarUnitYear … Read more
As of Xcode 6.0 Beta 5, it is now possible to import your own frameworks into a playground. This provides a way to share code between your applications and playgrounds, which can both import your frameworks. To do this: Your playground must be in the same workspace as the project that produces your framework. Your … Read more
You should use the reduce method to sum your sequence elements as follow: Xcode Xcode 10.2+ • Swift 5 or later extension Sequence where Element: AdditiveArithmetic { /// Returns the total sum of all elements in the sequence func sum() -> Element { reduce(.zero, +) } } extension Collection where Element: BinaryInteger { /// Returns … Read more
Xcode 6 beta 4 added two functions to iterate on ranges with a step other than one: stride(from: to: by:), which is used with exclusive ranges and stride(from: through: by:), which is used with inclusive ranges. To iterate on a range in reverse order, they can be used as below: for index in stride(from: 5, … Read more
Xcode’s Playgrounds for Swift don’t work like regular apps; they aren’t being run just once. The objects created stay in memory and can be inspected until you change the code, at which point the whole playground is reevaluated. When this happens, all previous results are discarded and while all object will be deallocated, you won’t … Read more
While you can run a run loop manually (or, for asynchronous code that doesn’t require a run loop, use other waiting methods like dispatch semaphores), the “built-in” way we provide in playgrounds to wait for asynchronous work is to import the XCPlayground framework and set XCPlaygroundPage.currentPage.needsIndefiniteExecution = true. If this property has been set, when … Read more