Change scope and scroll to selected date

[wimhaanstra]

I am trying out your component and after a couple of issues, I got most of it working.

What I am trying to achieve is the following:

1. Display the .Month scope
2. User selects a date
3. Change scope of calendar to '.Week'
4. Show selected date in the week scope

Step 1 to 3 works, animated, so that looks great, but I can't seem to be able to scroll the .Week scope to the right page.

I implemented my code like this:

func calendar(calendar: FSCalendar!, didSelectDate date: NSDate!) {
    if (calendar.scope == FSCalendarScope.Month) {
        calendar.setScope(FSCalendarScope.Week, animated: true)
        calendar.selectDate(date, scrollToDate: true)
    }
    else {
        self.navigationItem.rightBarButtonItem = nil;
    }
}

The problem with this method is that it crashes with the following error message:

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'request for number of items before section 2386 when there are only 1560 sections in the collection view'
*** First throw call stack:
(
    0   CoreFoundation                      0x0000000104e7b9b5 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010456ddeb objc_exception_throw + 48
    2   CoreFoundation                      0x0000000104e7b81a +[NSException raise:format:arguments:] + 106
    3   Foundation                          0x00000001041bab72 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 198
    4   UIKit                               0x00000001032988d0 -[UICollectionViewData numberOfItemsBeforeSection:] + 229
    5   UIKit                               0x000000010329897f -[UICollectionViewData globalIndexForItemAtIndexPath:] + 52
    6   UIKit                               0x000000010324ea98 -[UICollectionView cellForItemAtIndexPath:] + 111
    7   FSCalendar                          0x00000001027cb1e0 -[FSCalendar collectionView:shouldSelectItemAtIndexPath:] + 96
    8   FSCalendar                          0x00000001027cf7f2 -[FSCalendar selectDate:scrollToDate:forPlaceholder:] + 786
    9   FSCalendar                          0x00000001027cf4c9 -[FSCalendar selectDate:scrollToDate:] + 105
    10  Symagic                             0x000000010231fa78 _TFC7Symagic19MonthViewController8calendarfS0_FTGSQCSo10FSCalendar_13didSelectDateGSQCSo6NSDate__T_ + 568
    11  Symagic                             0x000000010231fca7 _TToFC7Symagic19MonthViewController8calendarfS0_FTGSQCSo10FSCalendar_13didSelectDateGSQCSo6NSDate__T_ + 71
    12  FSCalendar                          0x00000001027d12f1 -[FSCalendar didSelectDate:] + 369
    13  FSCalendar                          0x00000001027cae2f -[FSCalendar collectionView:didSelectItemAtIndexPath:] + 399
    14  UIKit                               0x000000010323e81b -[UICollectionView _selectItemAtIndexPath:animated:scrollPosition:notifyDelegate:] + 684
    15  UIKit                               0x000000010325f6bd -[UICollectionView touchesEnded:withEvent:] + 574
    16  UIKit                               0x0000000102c57173 forwardTouchMethod + 349
    17  UIKit                               0x0000000102c5723c -[UIResponder touchesEnded:withEvent:] + 49
    18  UIKit                               0x0000000102c57173 forwardTouchMethod + 349
    19  UIKit                               0x0000000102c5723c -[UIResponder touchesEnded:withEvent:] + 49
    20  UIKit                               0x0000000102acb15f -[UIWindow _sendTouchesForEvent:] + 835
    21  UIKit                               0x0000000102acbd4d -[UIWindow sendEvent:] + 865
    22  UIKit                               0x0000000102a802ae -[UIApplication sendEvent:] + 263
    23  UIKit                               0x0000000102a5c36c _UIApplicationHandleEventQueue + 6693
    24  CoreFoundation                      0x0000000104da7b21 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    25  CoreFoundation                      0x0000000104d9da4c __CFRunLoopDoSources0 + 556
    26  CoreFoundation                      0x0000000104d9cf03 __CFRunLoopRun + 867
    27  CoreFoundation                      0x0000000104d9c918 CFRunLoopRunSpecific + 488
    28  GraphicsServices                    0x0000000108461ad2 GSEventRunModal + 161
    29  UIKit                               0x0000000102a6199e UIApplicationMain + 171
    30  Symagic                             0x00000001022f970d main + 109
    31  libdyld.dylib                       0x0000000105b7e92d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

Any tips?

[WenchaoD]

Why did you select a date which had already been selected?

[wimhaanstra]

Well, after the user selects the date, I want the scope to change and then scroll to the selected date, so I hoped I could force the week mode to scroll there.

[WenchaoD]

OK, I'll take a look at it tomorrow.

[wimhaanstra]

The problem mentioned above isn't solely happening when selecting a date, but switching the scope of the calendar causes this error a lot of times for me.

The crash happens on the first line of:

- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath

FSCalendarCell *cell = (FSCalendarCell *)[collectionView cellForItemAtIndexPath:indexPath];

Switching to a Week scope, probably causes the indexPath to become invalid.

[WenchaoD]

Hi @depl0y
Can you use this as a temporary solusion?

- (void)calendar:(FSCalendar *)calendar didSelectDate:(NSDate *)date
{
    if (calendar.scope == FSCalendarScopeMonth) {
        [calendar setScope:FSCalendarScopeWeek animated:YES];
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            calendar.currentPage = date;
        });
    }
}

You should translate it to swift.
I know it's not an appropriate way, but I'll find one eventually.

[zjmdp]

The issue also puzzle me a lot..

[WenchaoD]

Fixed