当我获取 NSFileModificationDate 时获取 EXEC_BAD_ACCESS
我尝试获取文件的最后修改日期：
NSFileManager *fm = [[NSFileManager alloc] init];
NSError *err;
NSDate *lastModif = [[fm attributesOfItemAtPath:filename error:&err] objectForKey:NSFileModificationDate];//filename is ok ;-)
if(err == nil) {
[lastModif retain];
//I can put a NSLog of lastModif here, it works !!
NSTimeInterval lastModifDiff = [lastModif timeIntervalSinceNow];//crash here
}
我不明白为什么 NSDate 似乎已发布，为什么保留不保留它。
谢谢你，如果你有什么想法...
I try to get the last modification date of a file:
NSFileManager *fm = [[NSFileManager alloc] init];
NSError *err;
NSDate *lastModif = [[fm attributesOfItemAtPath:filename error:&err] objectForKey:NSFileModificationDate];//filename is ok ;-)
if(err == nil) {
[lastModif retain];
//I can put a NSLog of lastModif here, it works !!
NSTimeInterval lastModifDiff = [lastModif timeIntervalSinceNow];//crash here
}
I don't understand why the NSDate seems to be released, why the retain does not retain it.
Thank you if you have any idea...
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您不需要保留
lastModif。我认为当您使用它执行 NSLog 或之后对其执行任何操作时，您可能会尝试将lastModifDiff视为某种对象。NSTimeInterval是 double 的 typedef，因此您需要将其视为 double 或[NSNumber numberWithDouble:lastModifDiff]如果您想像对象一样使用它。You don't need to retain
lastModif. I think you might be trying to treatlastModifDiffas an object of some sort when you do an NSLog with it or whatever you do with it afterwards.NSTimeIntervalis a typedef to a double so you need to treat it as a double or[NSNumber numberWithDouble:lastModifDiff]if you want to use it like an object.我遇到了同样的问题，但这篇文章似乎密切相关：
NSDate : timeIntervalSinceNow crash
我正在写一组简单的函数 - startClock/endClock - 使用 NSDate 确定游戏循环中的 FPS。除了 timeIntervalSinceNow 崩溃之外，声称我之前设置的 NSDate 对象不存在。
我知道，当我调用 startClock 时，NSDate 对象的保留计数为 1，但我的理论是，NSDate 实例在内部被操纵为当它们感到无聊并且感觉没有用时自动释放。
使用保留/释放来承担这些轻浮且短暂的 NSDate 对象的所有权对我来说很有效。
I'm having the same problem, but this post seemed germane:
NSDate : timeIntervalSinceNow crash
I'm writing a simple set of functions- startClock/endClock -using NSDate to determine FPS in my game loop. Except that timeIntervalSinceNow crashes, claiming that my earlier set NSDate object doesn't exist.
I know for a fact that the NSDate object has a retain count of 1 when I call startClock, but my theory is that NSDate instances are internally rigged to auto-release when they get bored and aren't feeling useful.
Using retain/release to assume ownership of these flighty and ephemeral NSDate objects worked for me.