从 NSMutableArray 中提取 NSDictionary

发布于 2024-12-10 08:29:37 字数 1383 浏览 0 评论 0原文

我需要从 NSMutableArray 中提取 NSDictionary，并从该字典中提取一个对象。代码应该很简单，但我在 NSDictionary 声明上一直出现 SIGABRT 错误。

-(void)calcolaConto {
        conto = [[NSNumber alloc] initWithDouble:0];
    for (int i=0; [shoppingListItems count]; ++i) {
        NSDictionary *dictVar = (NSDictionary *) [shoppingListItems objectAtIndex:i]; //<-- SIGABRT
        NSNumber *IO = (NSNumber *) [dictVar objectForKey:@"incout"];
        NSNumber *priceValue = (NSNumber *) [dictVar objectForKey:@"price"];
        if ([IO isEqualToNumber:[NSNumber numberWithInt:0]]) {
            conto = [NSNumber numberWithDouble:([conto doubleValue] + [priceValue doubleValue])];
        } else if ([IO isEqualToNumber:[NSNumber numberWithInt:1]]) {
            conto = [NSNumber numberWithDouble:([conto doubleValue] - [priceValue doubleValue])];
        }
        NSLog(@"Valore %@", conto);
    }
}

“shoppingListItems”是这样创建的：

    NSMutableDictionary *rowDict = [[NSMutableDictionary alloc] initWithCapacity:6];
    [rowDict setObject:primaryKeyValue forKey: ID];
    [rowDict setObject:itemValue forKey: ITEM];
    [rowDict setObject:priceValue forKey: PRICE];
    [rowDict setObject:groupValue forKey: GROUP_ID];
    [rowDict setObject:incOut forKey:INC_OUT];
    [rowDict setObject:dateValue forKey: DATE_ADDED];
    [shoppingListItems addObject: rowDict];

原文

I need to extract a NSDictionary from a NSMutableArray, and extract an object from that dictionary.
The code should be quite easy, but I keep having a SIGABRT error on the NSDictionary declaration.

-(void)calcolaConto {
        conto = [[NSNumber alloc] initWithDouble:0];
    for (int i=0; [shoppingListItems count]; ++i) {
        NSDictionary *dictVar = (NSDictionary *) [shoppingListItems objectAtIndex:i]; //<-- SIGABRT
        NSNumber *IO = (NSNumber *) [dictVar objectForKey:@"incout"];
        NSNumber *priceValue = (NSNumber *) [dictVar objectForKey:@"price"];
        if ([IO isEqualToNumber:[NSNumber numberWithInt:0]]) {
            conto = [NSNumber numberWithDouble:([conto doubleValue] + [priceValue doubleValue])];
        } else if ([IO isEqualToNumber:[NSNumber numberWithInt:1]]) {
            conto = [NSNumber numberWithDouble:([conto doubleValue] - [priceValue doubleValue])];
        }
        NSLog(@"Valore %@", conto);
    }
}

"shoppingListItems" is created in this way:

    NSMutableDictionary *rowDict = [[NSMutableDictionary alloc] initWithCapacity:6];
    [rowDict setObject:primaryKeyValue forKey: ID];
    [rowDict setObject:itemValue forKey: ITEM];
    [rowDict setObject:priceValue forKey: PRICE];
    [rowDict setObject:groupValue forKey: GROUP_ID];
    [rowDict setObject:incOut forKey:INC_OUT];
    [rowDict setObject:dateValue forKey: DATE_ADDED];
    [shoppingListItems addObject: rowDict];

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一念一轮回 2024-12-17 08:29:37

问题是你的循环永远不会停止。您应该使用:

for (NSUInteger i = 0; i < [shoppingListItems count]; i++) {

或:

for (NSDictionary* dictVar in shoppingListItems) {

以便您不会尝试访问越界元素。在你的
当前循环 i 将递增，直到达到 [shoppingListItems count]
它超出了数组的末尾，因此 objectAtIndex 将抛出异常。

The problem is that your loop never stops. You should use:

for (NSUInteger i = 0; i < [shoppingListItems count]; i++) {

or:

for (NSDictionary* dictVar in shoppingListItems) {

so that you do not try to access an element that is out of bounds. In your
current loop i will be incremented until it reaches [shoppingListItems count]
which is beyond the end of the array, so objectAtIndex will throw an exception.

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