crash in pageviewscrollview

Thread : Crashed: com.apple.main-thread
0  QuartzCore                     0x2b7d1984 CA::Display::DisplayLink::get_link(CA::Display::Display*, __CFRunLoop*, X::List<__CFString const*> const*) + 239
1  QuartzCore                     0x2b7d1905 CA::Display::DisplayLink::get_link(CA::Display::Display*, __CFRunLoop*, X::List<__CFString const*> const*) + 112
2  QuartzCore                     0x2b7d1723 CA::Display::DisplayLinkItem::update_link(__CFRunLoop*) + 162
3  QuartzCore                     0x2b7f4823 CA::Display::DisplayLinkItem::dispatch() + 170
4  QuartzCore                     0x2b7f4643 CA::Display::DisplayLink::dispatch_items(unsigned long long, unsigned long long, unsigned long long) + 366
5  IOMobileFramebuffer            0x306f7c07 IOMobileFramebufferVsyncNotifyFunc + 90
6  IOKit                          0x29691001 IODispatchCalloutFromCFMessage + 256
7  CoreFoundation                 0x286cd24d __CFMachPortPerform + 132
8  CoreFoundation                 0x286dd7cb __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 34
9  CoreFoundation                 0x286dd767 __CFRunLoopDoSource1 + 346
10 CoreFoundation                 0x286dbd69 __CFRunLoopRun + 1608
11 CoreFoundation                 0x28628201 CFRunLoopRunSpecific + 476
12 CoreFoundation                 0x28628013 CFRunLoopRunInMode + 106
13 GraphicsServices               0x300f9201 GSEventRunModal + 136
14 UIKit                          0x2bdf4a09 UIApplicationMain + 1440
15 PageViewScrollView             0x000e27b0 main (AppDelegate.swift:14)
16 libdyld.dylib                  0x3760daaf start + 2