遇到一个 unrecognized selector sent to instance 的问题

[DavidHu]

写一个collectionViewController, 调用他的dataSource里面的一个自定义函数，结果调用不到，然后就crash了。

//ClassCalendarCollectionViewController.m
ClassCalendarDataSource *classDataSource = (ClassCalendarDataSource *)self.collectionView.dataSource;
classDataSource.configureWeekViewBlock = ^(WeekReuse *weekReuseView, NSString *kind, NSIndexPath *indexPath) {
if ([kind isEqualToString:@"WeekReuse"]) {
            for (int i = 0; i < 7; i++) {
                NSLog(@"will print: %@", weekDay[i]);
                weekReuseView.WeekTitle.text = [NSString stringWithFormat:weekDay[i], indexPath.item +1];
            }
        }
    };

//ClassCalendarDataSource.h
typedef void (^ConfigureWeekViewBlock)(WeekReuse *weekReuseView, NSString *kind, NSIndexPath *indexPath);
@interface ClassCalendarDataSource : NSObject <UICollectionViewDataSource>
@property (copy, nonatomic) ConfigureWeekViewBlock configureWeekViewBlock;
@end

这个是在学习着一个GitHub的项目在写，前辈指点我说要有这个函数的实现才行，但是原项目就没有实现，只是在几个需要的地方调用了一下
原项目地址： https://github.com/objcio/issue-3-collection-view-layouts.git
请教各位怎么回事

[DavidHu]

= =自己顶一下，还是没解决问题啊……