Which method of managing tasks or events is the slowest?

The slowest method of managing tasks or events in iOS is usually considered to be polling — periodically checking the status of a task or event at a set interval.

Polling requires constant querying, even if the event has not occurred, leading to excessive resource consumption and delays. In contrast, more efficient mechanisms include:

• Event handlers
• Delegates
• Notifications
• Asynchronous callbacks

For example, instead of checking every second whether a file has loaded, it is better to use a delegate or a closure that is called upon completion of the load.

Thus, polling is the slowest and least efficient way to manage tasks in iOS.