Objective-C none nil 数组在 if/else 语句中显示为 nil

发布于 2024-12-06 04:48:23 字数 686 浏览 0 评论 0原文

以下代码未按预期工作。我在创建视图之后但在显示之前设置一个数组。我使用 NSLog 来测试数组是否已设置，但 if/else 将数组视为空。

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    NSLog(@"Planlist is nil %d / has %d objects", (planListArr == nil), [planListArr count]);

    if (planListArr == nil || [planListArr count] == 0) { ... }
    else {
        NSLog(@"Planlist is empty");
    }
}

日志

2011-09-25 13:54:39.764 myVI[2938:13303] Planlist is nil 0 / has 8 objects
2011-09-25 13:54:39.765 myVI[2938:13303] Planlist is empty

计划列表定义为

NSArray *planListArr;

@property (nonatomic, retain) NSArray *planListArr;

原文

The following code is not working as expected. I am setting an array after creating a view but before displaying. I used NSLog to test that the array is set but the if/else sees the array as empty.

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    NSLog(@"Planlist is nil %d / has %d objects", (planListArr == nil), [planListArr count]);

    if (planListArr == nil || [planListArr count] == 0) { ... }
    else {
        NSLog(@"Planlist is empty");
    }
}

Logs

2011-09-25 13:54:39.764 myVI[2938:13303] Planlist is nil 0 / has 8 objects
2011-09-25 13:54:39.765 myVI[2938:13303] Planlist is empty

PlanList is defined as

NSArray *planListArr;

@property (nonatomic, retain) NSArray *planListArr;

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你不是我要的菜∠ 2024-12-13 04:48:23

if (planListArr == nil || [planListArr count] == 0) { ... }
else {
    NSLog(@"Planlist is empty");
}

展开后，这就变成了：

if (planListArr == nil || [planListArr count] == 0) {
    ...
} else {
    NSLog(@"Planlist is empty");
}

所以基本上，看起来你的 NSLog() 语句位于错误的分支中。

if (planListArr == nil || [planListArr count] == 0) { ... }
else {
    NSLog(@"Planlist is empty");
}

Expanded, this becomes:

if (planListArr == nil || [planListArr count] == 0) {
    ...
} else {
    NSLog(@"Planlist is empty");
}

So basically, it looks like you have your NSLog() statement in the wrong branch.

回复收藏 0 原文

往事随风而去 2024-12-13 04:48:23

(!plainListArray && [plainListArray count]>0) ? NSLog(@"PlainList array has %d items",[plainListArray count] : NSLog(@"Oops! Array is not been initialized or it has no items");

(!plainListArray && [plainListArray count]>0) ? NSLog(@"PlainList array has %d items",[plainListArray count] : NSLog(@"Oops! Array is not been initialized or it has no items");

回复收藏 0 原文

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