iPhone-scheduledTimerWithTimeInterval 是否保留 userInfo 参数？
在那段代码中，我有两个 NSLog 都表示 dict 的保留计数为 1。 由于如果数组中有很多对象，计时器可能会在很长一段时间内触发，我可以保留给用户信息的字典吗？因为我猜它是自动释放的，而scheduledTimerWithTimeInterval似乎没有保留它。
理论上？ 实际上？
- (void) doItWithDelay
{
NSArray* jobToDo = /* get an autorelease array */
NSTimeInterval nextLaunch = 0.1;
int i=1;
for (NSDictionary* dict in jobToDo) {
NSLog(@"dict %d has %d retain count", i++, [dict retainCount]);
// HERE [dict retain] ???
[NSTimer scheduledTimerWithTimeInterval:nextLaunch target:self selector:@selector(doIt:) userInfo:dict repeats:NO];
nextLaunch += 1.0;
}
}
- (void) doIt:(NSTimer*)theTimer
{
NSDictionary* dict = [theTimer userInfo];
NSLog(@"dict has now %d retain count", [dict retainCount]);
// Do some stuff with dict
}
In that piece of code, I have both NSLog that says dict has a retain count of 1.
As the timer can be triggered in a long time if there are many objects into the array, May I retain dict given into user info ? Because I guess it's autorelease, and the scheduledTimerWithTimeInterval does not seems to retain it.
Theoricaly ?
Practically ?
- (void) doItWithDelay
{
NSArray* jobToDo = /* get an autorelease array */
NSTimeInterval nextLaunch = 0.1;
int i=1;
for (NSDictionary* dict in jobToDo) {
NSLog(@"dict %d has %d retain count", i++, [dict retainCount]);
// HERE [dict retain] ???
[NSTimer scheduledTimerWithTimeInterval:nextLaunch target:self selector:@selector(doIt:) userInfo:dict repeats:NO];
nextLaunch += 1.0;
}
}
- (void) doIt:(NSTimer*)theTimer
{
NSDictionary* dict = [theTimer userInfo];
NSLog(@"dict has now %d retain count", [dict retainCount]);
// Do some stuff with dict
}
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苹果NSTimer文档说它会保留userInfo。以下引用自文档...
你的第二个 NSLog 说 1，所以我猜它已经被自动释放了，但计时器仍然保留它。
编辑：正如 bbum 所建议的，我们不应该依赖保留计数。所以我们很幸运，医生清楚地说明了这一点。
Apple NSTimer document say that it will retain the userInfo. Below is quoted from the document...
Your second NSLog say 1, so i guess it already been autoreleased but the timer still retain it.
EDIT: As bbum suggested, we should not rely on retain count. So we're lucky that the doc state it clearly.
正如 Khomsan 所说，文档明确指出该对象被保留。
故事结束。
retainCount没用；不要调用它。对象的绝对保留计数是一个实现细节。As Khomsan said, the docs explicitly state that the object is retained.
End of story.
retainCountis useless; don't call it. The absolute retain count of an object is an implementation detail.在尝试获取其 userInfo 之前不要使 NSTimer 无效。
do not invalidate NSTimer before attempting to its userInfo.