Flutter FutureOr

When you await an asynchronous function, the execution of the code within the caller suspends while the async operation is executed . When the operation is completed, the value of what was awaited is contained within a Future object.

And then is use one by one step of code, store data in variable and then move to next . Example: If I click in follow button until data store in variable it continuously retrieve some data to store and not allow next function to run, and if one task is complete than move to another.4 Şub 2019

. whenComplete will fire a function either when the Future completes with an error or not, instead . then will fire a function after the Future completes without an error. This is the asynchronous equivalent of a “finally” block.