iOS開發初學者,我會嘗試實現一個應用程序,它顯示一個XML文件的RSS源。EXC_BAD_ACCESS與NSXMLParser和ARC
在我的UITableView
類的viewDidLoad
中,我使用UIActivityIndicator
來等待數據加載。
但是,在應用程序將回到主線程的那一刻,我在parseXMLStart
函數的末尾添加了EXC_BAC_ACCESS
代碼2。我不明白爲什麼...
這裏的錯誤消息:
Thread 6 : 0-[NSXMLParser dealloc]
Message : EXC_BAC_ACCESS (code=2, address=0xc)
Line : 0xbb0840: movl (%eax,%ecx), %ecx
我不知道什麼和在哪裏是我的錯誤。我該如何解決它?
這裏是我的代碼:
=> Class Type :: UITableViewController
>> Header
@interface DataListViewController : UITableViewController {
UIActivityIndicatorView *activityView;
NSMutableArray *dataFromXML;
}
- (void)parseXMLStart;
- (void)parseXMLDone;
@end
>> Main
@implementation DataListViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
self.title = @"View 1";
activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
activityView.center = self.view.center;
[self performSelectorInBackground:@selector(parseXMLStart) withObject:nil];
[activityView startAnimating];
[activityView setHidesWhenStopped:YES];
[self.view addSubview:activityView];
}
#pragma mark - UIActivityIndicator Methods
- (void)parseXMLStart
{
// To Show the animation
sleep(1);
dataFromXML = [[NSMutableArray alloc] init];
// COMMENT TO TEST /*
[dataFromXML addObject:@"Element 1"];
[dataFromXML addObject:@"Element 2"];
[dataFromXML addObject:@"Element 3"];
// */ COMMENT TO TEST
// ------------------------------------------------------------------------------------------------------------------------------------
// UNCOMMENT TO TEST
/*
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"words" ofType:@"xml"];
NSURL *url = [[NSURL alloc] initWithString:[[NSString stringWithFormat:@"file://%@",filePath] stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]];
XML2ObjectParser *parserWords = [[XML2ObjectParser alloc] parseXMLAtURL:url toObject:@"Word" parseError:nil];
NSLog(@">> parserWords Items Count :: %i", parserWords.items.count);
for (int i = 0; i < [parserWords.items count]-1; i++) {
Word *aWord = [[Word alloc] init];
aWord = (Word *)[[parserWords items] objectAtIndex:i];
[dataFromXML addObject:aWord];
}
NSLog(@">> dataFromXML Count :: %i", dataFromXML.count);
*/
// UNCOMMENT TO TEST
// --------------------------------------------------------------------------------------------------------------------------------------------
// EXC_BAD_ACCESS (code=2, address=0xc)
// Thread 6 : 0-[NSXMLParser dealloc]
// 0xbad840: movl (%eax,%ecx), %ecx
// --------------------------------------------------------------------------------------------------------------------------------------------
[self performSelectorOnMainThread:@selector(parseXMLDone) withObject:nil waitUntilDone:YES];
}
- (void)parseXMLDone
{
[activityView stopAnimating];
[self.tableView reloadData];
}
# pragma mark - Table View Method
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [dataFromXML count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellID = @"CellID";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellID];
}
cell.textLabel.text = [dataFromXML objectAtIndex:[indexPath row]];
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
DataListDetailViewController *_dataListDetailViewController = [[DataListDetailViewController alloc] init];
_dataListDetailViewController.title = [dataFromXML objectAtIndex:[indexPath row]];
[self.navigationController pushViewController:_dataListDetailViewController animated:YES];
}
@end
幾件事情...... 1)爲什麼'XML2ObjectParser'是'NSXMLParser'的子類?它使用一個,但不作爲一個。 2)調用'alloc'而不調用某個'init'方法通常是錯誤的。 3)通過在您使用的構建/運行方案中啓用殭屍並啓用Objective-C異常的斷點,您應該能夠獲得更好的信息。 –