Question

我有一个UIViewController。我使用navigationItem的rightBarButtonItem作为“重新加载按钮”。当按下重新加载按钮时，我使用leftBarButtonItem显示活动指示器，同时应用程序正在处理要重新加载的数据。这里一切都很好。
这是一些代码：

- (void)initSpinner {
    activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
    activityButton = [[UIBarButtonItem alloc] initWithCustomView: activityIndicator];
    self.navigationItem.leftBarButtonItem = activityButton;
}

- (void)spinBegin {
    [activityIndicator startAnimating];
}

- (void)spinEnd {
    [activityIndicator stopAnimating];
}
- (void)viewDidLoad {
     [self initSpinner];
     [super viewDidLoad];
    //more stuff going on here....
}
-(void) loadView{
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(refreshFeeds:)];
}

现在我被要求改变一下逻辑 rightBarButtonItem保持原样。 leftBarButtonItem仍然显示活动指示器，但是当没有处理时，它应该显示另一个按钮，按下时将显示一个新视图（对于某些信息）。
所以我做了这些改变：

- (void)initSpinner {
    activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
    activityButton = [[UIBarButtonItem alloc] initWithCustomView: activityIndicator];
}

- (void)spinBegin {
    self.navigationItem.leftBarButtonItem = activityButton;
    [activityIndicator startAnimating];
}

- (void)spinEnd {
    [activityIndicator stopAnimating];
     self.navigationItem.leftBarButtonItem =infoBarButton; //= [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(refreshFeeds:)] autorelease];
}
-(void) loadView{
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(refreshFeeds:)];

    if (infoBarButton == nil){
        UIImage *buttonImage = [UIImage imageNamed:@"info.png"];
        UIButton *aButton = [UIButton buttonWithType:UIButtonTypeCustom];
        [aButton setImage:buttonImage forState:UIControlStateNormal];
        aButton.frame = CGRectMake(0.0, 0.0, 25, 25);

        // Initialize the UIBarButtonItem
        infoBarButton = [[UIBarButtonItem alloc] initWithCustomView:aButton];

        // Set the Target and Action for aButton
        [aButton addTarget:self action:@selector(showInfo:) forControlEvents:UIControlEventTouchUpInside];


    }
    self.navigationItem.leftBarButtonItem = infoBarButton;
}

虽然它似乎正在工作（信息按钮就在那里，当我按下“重新加载”时，activityIndicator取代它直到处理完成），我在调试器控制台中得到以下内容：

__NSAutoreleaseNoPool(): Object 0x15ef30 of class UINavigationItem autoreleased with no pool in place - just leaking
 __NSAutoreleaseNoPool(): Object 0x1abd90 of class UIBarButtonItem autoreleased with no pool in place - just leaking
__NSAutoreleaseNoPool(): Object 0x1acb20 of class UIButton autoreleased with no pool in place - just leaking
__NSAutoreleaseNoPool(): Object 0x15ef30 of class UINavigationItem autoreleased with no pool in place - just leaking
__NSAutoreleaseNoPool(): Object 0x1ad030 of class UIActivityIndicatorView autoreleased with no pool in place - just leaking
__NSAutoreleaseNoPool(): Object 0x1ad030 of class UIActivityIndicatorView autoreleased with no pool in place - just leaking
__NSAutoreleaseNoPool(): Object 0x1a8c40 of class UINavigationButton autoreleased with no pool in place - just leaking
Object 0x941c of class NSCFString autoreleased with no pool in place - just leaking
//MORE similar messages following...

我做错了什么？我希望那里有人可以提供帮助...
提前谢谢。

Answer 1

您的媒体资源是否为retain？您正在执行alloc] init...，但在将它们分配给您的属性后不会释放它们。我建议查看Memory Management Guide

Answer 2

我的猜测是你在后台线程中运行“重新加载”任务，当它完成时，你从后台线程中调用spinEnd。如果后台线程没有自动释放池，您将看到这些警告。

由于您只应该从主线程中调用UIKit方法，因此您应该通过执行以下操作来调用spinEnd：

[self performSelectorOnMainThread:@selector(spinEnd) withObject:nil waitUntilDone:NO];

更改navigationItem的barButtonItem

2 个答案: