What is the reason for receiving a warning stating "this method is not suitable for execution on the main thread"?

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The reason for receiving this warning is that the method in question is a time-consuming or blocking operation that should be executed on a separate thread to prevent blocking the main thread. Performing such operations on the main thread can cause the user interface to become unresponsive and give the impression that the app has crashed. Therefore, it is recommended to run such methods on a background thread or use asynchronous methods that allow the main thread to continue executing while waiting for the operation to complete.