Question

可能重复：
Make UIAlertView blocking

在这个人身上撞了几个小时。

这就是我所拥有的：OrderDetailsViewController设置为UIAlertViewDelegate

我有一个从搜索表单接收信息的程序。它检查物品是否已经在订单上，如果没有，则继续添加物品。如果它看到重复，它会弹出UIAlertView询问用户想要做什么：有3个选项，“合并” - 将新数量添加到旧项目，“添加”副本作为单独的行项目，或“取消“扔掉新物品。我需要等待来自UIAlertView的答案，以便我可以继续添加欺骗或丢弃欺骗 - “委托”在委托中处理，但我仍然需要主程序的答案。

这是我到目前为止所拥有的：

 - (void)returnItemAndQty:(ProductsSearchController *)productsSearchController
         withItemsToAdd:(NSMutableArray *)itemsToAdd 
         withQty:(NSDictionary *)qtyToAdd andClose:(BOOL)close
{
if ([itemsToAdd count] == 0) {
    return;
}
Items *items;
for (int index = 0; index < [itemsToAdd count]; index++) {
    items = [itemsToAdd objectAtIndex:index];
    qtyAddedToOrder = [NSDecimalNumber decimalNumberWithString:[qtyToAdd objectForKey:items.ItemCode]];     
    NSLog(@"Item Code: %@", items.ItemCode);
    NSLog(@"Qty: %@", [qtyToAdd objectForKey:items.ItemCode]);
    NSError *error;

    //For handling duplicate items. . . 
    duplicateItemDisposition = -1; //Reset the dispostion for normal operation
    if([self isItemOnOrder:items.ItemCode])
    {
        int i = [self itemIsAlreadyOnOrder:itemAlreadyOnOrder withQty:qtyAddedToOrder];

        if (i == COMBINE || i == CANCEL){ //either Cancel or Combine was pressed.
            items.Checked = NO;
            if (![items.managedObjectContext save:&error])
            {
                NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            }
            continue;
        }
    }
    //Add the new item or duplicate if that's what you want
    OrdersDetails *newOrderDetail = [NSEntityDescription insertNewObjectForEntityForName:@"OrdersDetails" 
                                                                  inManagedObjectContext:self.managedObjectContext];

.//more code snipped, that handles the "ADD" or non-dupe
.
.

这是测试重复的地方。。

- (BOOL)isItemOnOrder:(NSString *)itemCode
{

 NSFetchRequest *request = [[NSFetchRequest alloc] init];

     NSEntityDescription *entity = [NSEntityDescription entityForName:@"OrdersDetails"
                                          inManagedObjectContext:managedObjectContext];
    [request setEntity:entity];

    NSSortDescriptor *sort = [[NSSortDescriptor alloc]initWithKey:@"Desc1" ascending:NO];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sort, nil];
    [request setSortDescriptors:sortDescriptors];
    [sort release];
    [sortDescriptors release];

    NSPredicate *pred = [NSPredicate predicateWithFormat:@"(ItemCode=%@ AND OrderID=%@)", itemCode, orders.OrderID];
    [request setPredicate:pred];

    NSError *error;
    NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:& error] mutableCopy];
   [request release];
   if (mutableFetchResults == nil) {
       itemAlreadyOnOrder = nil;
       return NO;
   }else if ([mutableFetchResults count] > 0){
       itemAlreadyOnOrder = [mutableFetchResults objectAtIndex:0];
       return YES;
   }else{
       itemAlreadyOnOrder = nil;
       return NO;
   }
}

在这里，它看到一个欺骗存在，UIAlertview委托它。。

- (int) itemIsAlreadyOnOrder:(OrdersDetails *)existingOrderDetail withQty:(NSDecimalNumber *)qty 
{
    if (existingOrderDetail == nil) {
    return -1;
    }

    UIAlertView *duplicateAlert = [[UIAlertView alloc] initWithTitle:[NSString stringWithFormat:@"Duplicate Item %@ found.",existingOrderDetail.ItemCode] message:@"Tap Combine to combine the items, Tap Add to add the duplicate item or Tap Cancel to discard the duplicate" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Combine", @"Add", nil];
    [duplicateAlert show];

    return duplicateItemDisposition;

    [duplicateAlert release];
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
// Cancel = 0, Combine = 1, Add = 2

    if (buttonIndex == CANCEL){
        duplicateItemDisposition = CANCEL;
    }else if (buttonIndex == COMBINE){
            duplicateItemDisposition = COMBINE;
            NSDecimalNumber *existingQty = [[NSDecimalNumber alloc] initWithDecimal:[itemAlreadyOnOrder.Qty decimalValue]];
            NSDecimalNumber *existingPrice = itemAlreadyOnOrder.Price;
            NSDecimalNumber *newQty = [existingQty decimalNumberByAdding:qtyAddedToOrder];
            itemAlreadyOnOrder.ExtPrice = [newQty decimalNumberByMultiplyingBy:existingPrice];
           [existingQty release];
           NSError *error;
           if (![itemAlreadyOnOrder.managedObjectContext save:&error]){
        NSLog(@"Error saving. %@, %@", error, [error userInfo]);
               [self handleFreeGoods:itemAlreadyOnOrder];
           }else if (buttonIndex == ADD){
               duplicateItemDisposition = ADD;
           }
}

现在我在这里阅读有关在后台线程中使用NSCondition的内容，但我不知道这意味着什么。我查了一下NSCondition，它不是很有启发性。

关于如何暂停执行的任何想法？

Answer 1

UIAlertView无法阻止，因为它会显示在runloop的末尾。方法itemIsAlreadyOnOrder:不返回指示应对重复条目执行的操作的值，而UIAlertView中的委托方法需要通知您的控制器已解决相关项。跟踪相关对象（_objectToVerify或类似的东西），并在UIAlertView的委托方法中调用基于用户选择的方法，该方法将作用于_objectToVerify。

Answer 2

我不知道这可能会改变你当前的设计多少，但是Cocoa设计模式会有一个提醒警报不返回任何内容的方法，所以像伪代码中的if (duplicate) showAlertView。然后在警报视图的委托中，根据用户输入调用实际处理副本处理的方法。

ios UIAlertView：提醒我等待我的回复

2 个答案: