应用程序因WebView崩溃

时间:2011-02-06 21:52:36

标签: iphone uiwebview crash

在我的应用程序中,我使用UIwebview来显示网站,但每当我点击后退按钮并开始在应用程序中的其他部分玩游戏时,该应用程序大多会崩溃,没有任何理由。我怀疑webview导致了这个问题,因为它只在我尝试打开webview时崩溃。

我已经使用NSURLConnection加载webview并制作了webview,在视图中将连接对象设为nil将消失方法。

@implementation NewsWebSiteViewController

@synthesize connection,rcvdData,spinner1,currentSite,webView,newsWebsite;

- (void)viewDidLoad {
    [super viewDidLoad];
    @try {
        self.webView.delegate=self;
        [UIApplication sharedApplication].networkActivityIndicatorVisible=YES;
        self.title= self.newsWebsite.title;
        self.webView.backgroundColor =[UIColor groupTableViewBackgroundColor];
        self.spinner1 = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
        CGRect center = [self.view bounds];
        CGSize winCenter = center.size;
        CGPoint pont = CGPointMake(winCenter.width/2,winCenter.height/2);
        [spinner1 setCenter:pont];
        [self.view addSubview:spinner1];
        [self.spinner1 startAnimating];
        NSString *url = newsWebsite.link;
        NSURLRequest *theReq =[NSURLRequest requestWithURL:[NSURL URLWithString:url] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:20.0];
        self.connection = [[NSURLConnection alloc] initWithRequest:theReq delegate:self];
        if(self.connection) {
            self.rcvdData = [[NSMutableData data] retain];
        }
        else {
        UIAlertView *alert = [[[UIAlertView alloc] initWithTitle:@"Error!" message:@"We are having a problem connecting to the internet, why not try again or try sometime later!.." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil] autorelease];
        [alert show];
        }
        webView.multipleTouchEnabled=YES;
        webView.scalesPageToFit=YES;
    }
    @catch (NSException * e) {
        }  
}

-(void) goBack {
    self.webView =nil;
    [self.navigationController popViewControllerAnimated:YES];
}

-(void) viewWillDisappear:(BOOL)animated {

    [self.connection cancel];
    self.connection=nil;
    [self.webView stopLoading];
    self.webView=nil;

    [UIApplication sharedApplication].networkActivityIndicatorVisible=NO;

    if (self.spinner1 ==nil) {

    }

    else {
        [self.spinner1 stopAnimating];
    }

}

-(void) webViewDidFinishLoad:(UIWebView *)webView {

    [UIApplication sharedApplication].networkActivityIndicatorVisible=NO;

    if (self.spinner1 ==nil) {

    }
    else {
        [self.spinner1 stopAnimating];
    }
}

-(void) viewDidAppear:(BOOL)animated  {
    [UIApplication sharedApplication].networkActivityIndicatorVisible=NO;

}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}


- (void)viewDidUnload {
    [super viewDidUnload];
}


-(void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [self.rcvdData setLength:0];
}


-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [self.rcvdData appendData:data];
}


-(void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    if (self.spinner1 ==nil) {
        }
    else {
        [self.spinner1 stopAnimating];
        }
    [connection release];
    [rcvdData release];
    UIAlertView *alert = [[[UIAlertView alloc] initWithTitle:@"Error!" message:@"We are having a problem connecting to the internet, why not try again or try sometime later!.." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil] autorelease];
    [alert show];
}


-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
    [connection release];
    [rcvdData release];
    NSString *url = newsWebsite.link;
    NSURL *url1 =  [NSURL URLWithString:url];
    [self.webView loadData:self.rcvdData MIMEType:@"text/html" textEncodingName:@"UTF-8" baseURL:url1];
}

- (void)dealloc {
    [super dealloc];
    [self.spinner1 release];
}

@end

1 个答案:

答案 0 :(得分:1)

首先,这是C / Objective-C中关于等式/不等式的小引物:

假设您有一个BOOL值(即可以是YES或NO,'On'或'Off','True'或'False'的值),称为isEnabled 。现在,如果我将此BOOL值(有时称为“标记”)指定为“是”,我可以有条件地测试其值,如下所示:

BOOL isEnabled = YES;

if (isEnabled)
{
   // value set to yes
}

除了上述内容之外,我还可以使用否定运算符(感叹号 - 也称为NOT运算符)来翻转isEnabled的值,并测试其相反的值:

BOOL isEnabled = YES;

// the following reads as "if is *not* enabled"
if (!isEnabled)
{
   // value set to no
}

现在当然在上面的示例中isEnabled设置为YES,因此条件将失败。但是,如果我们考虑以下示例,if的属性,如果else if在一系列if和{{1}中的任何位置“满足”(即,为真)它将执行其中的所有代码,然后忽略其他任何内容:

else if

虽然上面有两个冗余的BOOL isEnabled = NO; if (isEnabled) { // any code here will not run, as the above if condition will be false } else if (!isEnabled) { // this code will run, since the above condition (!isEnabled) will evaluate to true } else if (isEnabled) { // this code could never run, since the previous condition was true and all following else if's are ignored } else if (!isEnabled) { // this code could never run, since the previous condition was true and all following else if's are ignored } ,但它是演示条件代码如何工作的好方法。

因此,在else if方法中,您可以使用更简单的条件替换if,而不是空白if if else if条件:

webViewDidFinishLoad:

如果您对所有if和其他if进行了上述更改,请发布堆栈跟踪,我会看到它可能是什么。