FORMDataSource.m

- (void)deleteItemsAtIndexPaths:(NSArray *)indexPaths {
    NSArray *reloadedIndexPaths = [self safeIndexPaths:indexPaths];

    if (reloadedIndexPaths.count > 0) {
        [self.collectionView deleteItemsAtIndexPaths:reloadedIndexPaths];
    }
}

gistfile1.txt

2015-06-15 08:07:07.559 MyApplication[51976:5933010] Saved: <NSManagedObject: 0x7c8c1590> (entity: Order; id: 0x7c878c80 <x-coredata://18D1A6AB-9CE5-44EF-AAE4-59427BCCA1D0/Order/p16> ; data: {
    amountTendered = "$100.00";
    changeDue = "$22.00";
    companyID = 1;
    completedAt = nil;
    deviceID = 3;
    discountTotal = nil;
    emailAddress = nil;
    firstName = nil;
    ipAddress = "::1";
    lastName = nil;
    lineItems = <62706c69 73743030 d4010203 04050858 59542474 6f705824 6f626a65 63747358 24766572 73696f6e 59246172 63686976 6572>;
    orderNumber = "003-150615080707424";
    orderStatus = successful;
    orderTotal = "78.0";
    phoneNumber = nil;
    remoteID = 26;
    transactionDate = nil;
    transactions = <62706c69 73743030 d4010203 04050871 72542474 6f705824 6f626a65 63747358 24766572 73696f6e 59246172 63686976 6572>;
})
2015-06-15 08:07:07.559 MyApplication[51976:5933010] savedOrder: <NSManagedObject: 0x7c8c1590> (entity: Order; id: 0x7c878c80 <x-coredata://18D1A6AB-9CE5-44EF-AAE4-59427BCCA1D0/Order/p16> ; data: {
    amountTendered = "$100.00";
    changeDue = "$22.00";
    companyID = 1;
    completedAt = nil;
    deviceID = 3;
    discountTotal = nil;
    emailAddress = nil;
    firstName = nil;
    ipAddress = "::1";
    lastName = nil;
    lineItems = <62706c69 73743030 d4010203 04050858 59542474 6f705824 6f626a65 63747358 24766572 73696f6e 59246172 63686976 6572>;
    orderNumber = "003-150615080707424";
    orderStatus = successful;
    orderTotal = "78.0";
    phoneNumber = nil;
    remoteID = 26;
    transactionDate = nil;
    transactions = <62706c69 73743030 d4010203 04050871 72542474 6f705824 6f626a65 63747358 24766572 73696f6e 59246172 63686976 6572>;
})
2015-06-15 08:07:07.599 MyApplication[51976:5933010] negative or zero sizes are not supported in the flow layout
2015-06-15 08:07:07.600 MyApplication[51976:5933010] *** Assertion failure in -[UICollectionView _endItemAnimationsWithInvalidationContext:tentativelyForReordering:], /SourceCache/UIKit_Sim/UIKit-3347.44/UICollectionView.m:4072
2015-06-15 08:07:07.602 MyApplication[51976:5933010] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of items in section 2.  The number of items contained in an existing section after the update (6) must be equal to the number of items contained in that section before the update (6), plus or minus the number of items inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of items moved into or out of that section (0 moved in, 0 moved out).'
*** First throw call stack:
(
	0   CoreFoundation                      0x03890746 __exceptionPreprocess + 182
	1   libobjc.A.dylib                     0x03519a97 objc_exception_throw + 44
	2   CoreFoundation                      0x038905da +[NSException raise:format:arguments:] + 138
	3   Foundation                          0x01d42720 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 118
	4   UIKit                               0x02811e21 -[UICollectionView _endItemAnimationsWithInvalidationContext:tentativelyForReordering:] + 14566
	5   UIKit                               0x0280e536 -[UICollectionView _endItemAnimationsWithInvalidationContext:] + 48
	6   UIKit                               0x0280e2ed -[UICollectionView _updateRowsAtIndexPaths:updateAction:] + 374
	7   UIKit                               0x0280e374 -[UICollectionView deleteItemsAtIndexPaths:] + 48
	8   Form                                0x008cbae4 -[FORMDataSource deleteItemsAtIndexPaths:] + 196
	9   Form                                0x008d2676 __33-[FORMDataSource processTargets:]_block_invoke + 806
	10  Form                                0x008f8b1f +[FORMTarget filteredTargets:filtered:] + 1247
	11  Form                                0x008d2312 -[FORMDataSource processTargets:] + 178
	12  MyApplication                       0x00047d8b -[VPPrintCollectionViewController removeProcessOrderButton] + 379
	13  MyApplication                       0x00043728 -[VPPrintCollectionViewController initWithJSON:andInitialValues:] + 488
	14  MyApplication                       0x00036fab -[VPPaymentCollectionViewController printOrderReceipt] + 715
	15  MyApplication                       0x00037c66 __49-[VPPaymentCollectionViewController processOrder]_block_invoke + 998
	16  AFNetworking                        0x0058b44b __64-[AFHTTPRequestOperation setCompletionBlockWithSuccess:failure:]_block_invoke46 + 43
	17  libdispatch.dylib                   0x03d485ea _dispatch_call_block_and_release + 15
	18  libdispatch.dylib                   0x03d6abef _dispatch_client_callout + 14
	19  libdispatch.dylib                   0x03d506bb _dispatch_main_queue_callback_4CF + 993
	20  CoreFoundation                      0x037e98ee __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 14
	21  CoreFoundation                      0x037a75f0 __CFRunLoopRun + 2256
	22  CoreFoundation                      0x037a6a5b CFRunLoopRunSpecific + 443
	23  CoreFoundation                      0x037a688b CFRunLoopRunInMode + 123
	24  GraphicsServices                    0x063e32c9 GSEventRunModal + 192
	25  GraphicsServices                    0x063e3106 GSEventRun + 104
	26  UIKit                               0x020f0106 UIApplicationMain + 1526
	27  MyApplication                       0x0003f3da main + 138
	28  libdyld.dylib                       0x03d95ac9 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

Print.m

- (void)removeProcessOrderButton {
    NSMutableArray *hideTargets = [NSMutableArray new];
    FORMField *field = [self.dataSource fieldWithID:@"process_order"
                   includingHiddenFields:NO];
    if (field) {
        [hideTargets addObject:[FORMTarget hideFieldTargetWithID:field.fieldID]];
        [self.dataSource processTargets:hideTargets];
    }
}