NSPointerArray怪异的压缩 [英] NSPointerArray weird compaction

问题描述

我有一个弱的NSPointerArray，其中有一些NSObject已发布.在致电compact之前，我看到的是:

I have a weak NSPointerArray with some NSObject that has been released. Before calling compact what I see is:

(lldb) po [currentArray count]
1
(lldb) po [currentArray pointerAtIndex:0]
<nil>
(lldb) po [currentArray allObjects]
<__NSArrayM 0x16f04f00>(

)

这是有道理的，但是真正奇怪的是，当我在该数组上调用compact时，我看到了相同的值！计数仍然返回1，而pointerAtIndex:0是nil.

That makes sense, but what is really weird is that when I call compact on that array I see the same values! Count still returns 1 and pointerAtIndex:0 is nil.

为什么没有删除nil?

Why the nil hasn't been removed?

编辑

这是完整的代码(是的，它是XCTesting框架):

Here's the full code (yeah it's XCTesting framework):

- (void)testCompaction {
    __weak id testingPointer = nil;

    NSPointerArray *weakArray = [NSPointerArray weakObjectsPointerArray];

    @autoreleasepool {

        NSObject *someObj = [[NSObject alloc] init];

        testingPointer = someObj;

        [weakArray addPointer:(__bridge void*)testingPointer];

        NSLog(@"before compaction inside autorelease: testingPointer = %@ count = %d, allObjects = %@, pointerAtIndex:0 = %@, pointerAtIndex:0 class = %@", testingPointer, [weakArray count], [weakArray allObjects], [weakArray pointerAtIndex:0], [(id)[weakArray pointerAtIndex:0] class]);

        someObj = nil;
    }

    NSLog(@"before compaction outside autorelease: testingPointer = %@ count = %d, allObjects = %@, pointerAtIndex:0 = %@, pointerAtIndex:0 class = %@", testingPointer, [weakArray count], [weakArray allObjects], [weakArray pointerAtIndex:0], [(id)[weakArray pointerAtIndex:0] class]);

    [weakArray compact];

    NSLog(@"after compaction outside autorelease: testingPointer = %@ count = %d, allObjects = %@, pointerAtIndex:0 = %@, pointerAtIndex:0 class = %@", testingPointer, [weakArray count], [weakArray allObjects], [weakArray pointerAtIndex:0], [(id)[weakArray pointerAtIndex:0] class]);
}

并记录:

  before compaction inside autorelease: testingPointer = <NSObject: 0x7de7ff80> count = 1, allObjects = (
    "<NSObject: 0x7de7ff80>"
), pointerAtIndex:0 = <NSObject: 0x7de7ff80>, pointerAtIndex:0 class = NSObject
2015-07-20 14:27:14.062 AppetizeSuite copy[54144:9019054] before compaction outside autorelease: testingPointer = (null) count = 1, allObjects = (
), pointerAtIndex:0 = (null), pointerAtIndex:0 class = (null)
2015-07-20 14:27:22.615 AppetizeSuite copy[54144:9019054] after compaction outside autorelease: testingPointer = (null) count = 1, allObjects = (
), pointerAtIndex:0 = (null), pointerAtIndex:0 class = (null)   

为什么compact方法不删除第一个指针?显然，在调用compact之前是nil.

Why the compact method does not delete the first pointer? It's clearly a nil before calling compact.

推荐答案

我已经看到了相同的行为.这是一个公开的雷达故障报告: http://www.openradar.me/15396578

I've seen this same behavior. Here is an open radar bug report: http://www.openradar.me/15396578

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