SUNiL

DispatchGroup: You attach multiple work items to a group and schedule them for asynchronous execution on the same queue or different queues. When all work items finish executing, the group executes its completion handler.   You can also wait synchronously for all tasks in the group to finish executing.   DispatchGroup instance - Creates a new group to which you can assign block objects.   Functions: enter() - Explicitly indicates that a block has entered the group. wait() - Waits synchronously for the previously submitted work to finish. Can also used with TimeOut option- DispatchTime - Gives DispatchTimeoutResult leave() - Explicitly indicates that a block in the group finished executing. notify() - Schedules the submission of a block with the specified attributes to a queue when all tasks in the current group have finished executing. Can be used with & without QOS import  UIKit public typealias CompletionHandlerWithBoolStatus = ( _ status: Bool ) -...