iphone - iPhone-对象在NSTimed调用上不再支持已知的选择器

Question

我设置了一个计时器来重置对象的属性:

- (IBAction)open:(id)sender {
    int viewID = ((UIButton*)sender).tag;

    for (int i=0; i<[self.webViews count]; i++) {
        WebViewController* page = [self.webViews objectAtIndex:i];
        if (page.loadFinished == NO) {
            [page.webView stopLoading];
            [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(setLoadingNotFinished:) userInfo:page repeats:NO];   
        }
    }


- (void) setLoadingNotFinished:(WebViewController*)page {
    page.loadFinished = NO;
}

当输入setLoadingNotFinished方法时，发生此崩溃:

2011-04-25 04:34:22.358 MyApp[7823:207] -[__NSCFTimer setLoadFinished:]: unrecognized selector sent to instance 0x4b203d0
2011-04-25 04:34:22.360 MyApp[7823:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFTimer setLoadFinished:]: unrecognized selector sent to instance 0x4b203d0'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x00dca5a9 __exceptionPreprocess + 185
    1   libobjc.A.dylib                     0x00f1e313 objc_exception_throw + 44
    2   CoreFoundation                      0x00dcc0bb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
    3   CoreFoundation                      0x00d3b966 ___forwarding___ + 966
    4   CoreFoundation                      0x00d3b522 _CF_forwarding_prep_0 + 50
    5   MyApp                               0x00003a42 -[MainGridController setLoadingNotFinished:] + 66
    6   Foundation                          0x007ba749 __NSFireTimer + 125
    7   CoreFoundation                      0x00dab8c3 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 19
    8   CoreFoundation                      0x00dace74 __CFRunLoopDoTimer + 1220
    9   CoreFoundation                      0x00d092c9 __CFRunLoopRun + 1817
    10  CoreFoundation                      0x00d08840 CFRunLoopRunSpecific + 208
    11  CoreFoundation                      0x00d08761 CFRunLoopRunInMode + 97
    12  GraphicsServices                    0x010021c4 GSEventRunModal + 217
    13  GraphicsServices                    0x01002289 GSEventRun + 115
    14  UIKit                               0x0002ac93 UIApplicationMain + 1160
    15  MyApp                               0x000027e9 main + 121
    16  MyApp                               0x00002765 start + 53
)
terminate called after throwing an instance of 'NSException'

为什么会发生这种崩溃？
我不明白为什么找不到选择器。

设置了loadFinished属性，即使对该属性的第一个测试在调用NSTimer方法之前也可以运行，并且我在许多地方都使用了此属性。
页面在计时方法中不为零。
self.webViews是保留的NSMutableArray。

Answer 1

请再次检查代码。我纠正了。它有语法错误。

以下应解决此问题:
- (void) setLoadingNotFinished:(NSTimer *)myTimer { WebViewController *page = (WebViewController *)[myTimer userInfo]; page.loadFinished = NO; }
选择器方法接收NSTimer作为其参数，而不是userInfo。然后，使用NSTimer检索先前设置为userInfo的对象。

(在原始的-setLoadingNotFinished中，页面不是WebViewController，而是NSTimer。而且setLoadFinished被发送到NSTimer，后者无法识别它。)

请注意，错误消息告诉您选择器方法已发送到_NSCFTimer类的对象。这为您提供了有关错误性质的线索。