ios - The following delegate functions for iOS

Question

In the base.h It implement a delegate function

id<MADayViewDataSource> _dataSource;

@protocol MADayViewDataSource <NSObject>

- (NSArray *)dayView:(MADayView *)dayView eventsForDate:(NSDate *)date;
@end

In the base.m

- (void)setDataSource:(id <MADayViewDataSource>)dataSource {
    _dataSource = dataSource;
    [self reloadData];
}

- (id <MADayViewDataSource>)dataSource {
    return _dataSource;
}

- (void)reloadData {
    NSArray *events = [self.dataSource dayView:self eventsForDate:self.day];
}

In top Viewcontroller.h It implement the MADayViewDatasource delegate from base.h

      :UIViewController<MADayViewDataSource> { }

In base.m, It implement that delegate function

- (NSArray *)dayView:(MADayView *)dayView eventsForDate:(NSDate *)startDate {

So, my understanding of the code is when the function inside the base.m is called

[self.datasource dayView:self eventsForDate:self.day]; 

The self.datasource would call -(void)setDataSource <MADayViewDataSource>)dataSource {} which return the _datasource....etc anyway, I am lost..

My question what's sequence of fucntion being called? How does the datasource from base relate to the array returning from the delegate function from the top viewcontroller?