我有一个应用程序，可以在登录后为客户编制客户特定报告列表。这些报告出现了，我已经提出了一个＆＃34;视图＆＃34;应该下载PDF文件的按钮，然后在应用程序中查看。
在这个阶段，按下查看按钮时看起来好像有内存问题，我不知道如何找到问题所在。 HEre是我的代码：
#import "reportsTestViewController.h"
#import "ReportsDataObject.h"
#import "Session.h"
#import "AFNetworking.h"
@interface reportsTestViewController ()
@end
@implementation reportsTestViewController
@synthesize response;
@synthesize myDataIvar;
@synthesize viewReportPressed;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
reportsTable.delegate = self;
reportsTable.dataSource = self;
self.sections = [[NSMutableDictionary alloc] init];
[super viewDidLoad];
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
#pragma mark NSURLConnection Delegate Methods
//
//Create your request pointing to the test page
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.tesg.com.au/allCustBuild.php"] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:15.0];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
//initialize it when you create your connection
if (connection){
self.myDataIvar = [[NSMutableData alloc] init];
}
}
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
[self.myDataIvar setLength:0];
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
[self.myDataIvar appendData:data];
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
NSLog(@"Connection Failed: %@", error.userInfo);
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection{
//this is where you would parse the data received back from the server
NSString *responseString = [[NSString alloc] initWithData:self.myDataIvar encoding:NSUTF8StringEncoding];
NSLog(@"Received Data: %@",responseString);
[self setupReportsFromJSONArray:self.myDataIvar];
}
-(void)connectionWasASuccess:(NSData *)data{
[self setupReportsFromJSONArray:data];
}
-(void)setupReportsFromJSONArray:(NSData*)dataFromReportsArray{
BOOL found;
NSError *error;
// NSMutableArray *reportsArray = [[NSMutableArray alloc] init];
NSArray *arrayFromServer = [NSJSONSerialization JSONObjectWithData:dataFromReportsArray options:0 error:&error];
if(error){
NSLog(@"error parsing the json data from server with error description - %@", [error localizedDescription]);
}
else {
reportsArray = [[NSMutableArray alloc] init];
for(NSDictionary *eachReport in arrayFromServer)
{
ReportsDataObject *report = [[ReportsDataObject alloc] initWithJSONData:eachReport];
[reportsArray addObject:report];
NSString *c = [[eachReport objectForKey:@"title"] substringToIndex:3];
found = NO;
for (NSString *str in [self.sections allKeys])
{
if ([str isEqualToString:c])
{
found = YES;
}
}
if (!found)
{
[self.sections setValue:[[NSMutableArray alloc] init] forKey:c];
}
}
}
NSLog(@"Array Populated");
NSLog(@"%u reports found",reportsArray.count);
//Now you have your reportsArray filled up with all your data objects
for (NSDictionary *eachReport in arrayFromServer)
{
[[self.sections objectForKey:[[eachReport objectForKey:@"title"] substringToIndex:3]] addObject:eachReport];
}
// Sort each section array
for (NSString *key in [self.sections allKeys])
{
[[self.sections objectForKey:key] sortUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"title" ascending:YES]]];
}
[reportsTable reloadData];
}
-(void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(void)viewReportPressed:(UIButton*)button {
NSLog(@"Button successfully Pressed");
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
NSURL *URL = [NSURL URLWithString:@"http://tesg.com.au/portal/media/reports/1367365180_367 Collins Passive April 2013.pdf"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];
NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:nil destination:^NSURL *(NSURL *targetPath, NSURLResponse *theResponse) {
NSURL *documentsDirectoryPath = [NSURL fileURLWithPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]];
return [documentsDirectoryPath URLByAppendingPathComponent:[theResponse suggestedFilename]];
} completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {
NSLog(@"File downloaded to: %@", filePath);
}];
[downloadTask resume];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
NSUInteger count = [[self.sections allKeys] count];
NSLog(@"Number of sections: %d", count);
return count;
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
return [[[self.sections allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] objectAtIndex:section];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
//We check against table to make sure we are displaying the right number of cells
// for the appropriate table. This is so that things will work even if one day you
//decide that you want to have two tables instead of one.
{
NSUInteger count = [[self.sections valueForKey:[[[self.sections allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] objectAtIndex:section]] count];
NSLog(@"Number of rows in section: %d", count);
return count;
}
}
//- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView {
//return [[self.sections allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
// }
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = @"Cell";
UITableViewCell *cell =[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (!cell)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier];
}
//The beauty of this is that you have all your data in one object and grab WHATEVER you like
//This way in the future you can add another field without doing much.
NSUInteger count = [[self.sections allKeys] count];
if(count == 0){
cell.textLabel.text = @"no reports to show";
}
else{
NSDictionary *Reports = [[self.sections valueForKey:[[[self.sections allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] objectAtIndex:indexPath.section]] objectAtIndex:indexPath.row];
cell.textLabel.text = [Reports objectForKey:@"title"];
cell.detailTextLabel.text = [Reports objectForKey:@"building"];
UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:self action:@selector(viewReportPressed:) forControlEvents:UIControlEventTouchUpInside];
[button setTitle:@"View" forState:UIControlStateNormal];
button.frame = CGRectMake(180.0f, 5.0f, 150.0f, 30.0f);
[cell addSubview:button];
// in the future you can grab whatever data you need like this
//[currentReport buildingName], or [currentReport reportName];
}
return(cell);
}
@end
当在任何单元格中按下视图按钮时，我会按下NSLog说“＆＃39;”按钮＆＃39;但是在出错之后它会立即崩溃
[downloadTask resume]; Thread 1:EXC_BAD_ACCESS (code=2, address=0x0)
任何想法如何解决这个问题？
答案 0 :(得分：4)
如果您获得地址为EXC_BAD_ACCESS的{{1}}，则通常意味着在不允许0x0的情况下使用nil值。
在这种情况下，这是因为您的URL字符串无效。不允许有空格。因此，生成的nil变量为URL，这将导致您描述的行为。您可能希望百分比转义URL字符串，例如：
nil要在将来识别此类异常，您可以使用exception breakpoints，这通常有助于识别有问题的代码行。或者只是仔细检查您的代码，以了解您可能无意中将NSString *URLString = @"http://tesg.com.au/portal/media/reports/1367365180_367 Collins Passive April 2013.pdf";
NSURL *URL = [NSURL URLWithString:[URLString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
值传递给不接受它的方法的情况。
但是，如果您获得的nil值不是EXC_BAD_ACCESS，那么这通常是尝试使用以前取消分配的对象的结果。 （并非总是，但经常。幸运的是，ARC已经使这种问题不那么常见。）显然，这不是这种情况，但是您询问人们如何识别您尝试使用以前解除分配的对象的情况。
要诊断出这种情况，你通常会打开“僵尸”（见Running Your Application with Diagnostics）。顺便说一下，一旦你用僵尸完成诊断，请确保你关闭它们，因为你不想让僵尸保持打开状态（特别是在生产应用程序中）。
无论如何，在这种情况下，因为地址是0x0，它不是解除分配对象的结果，而是问题是0x0值的错误使用，由无效的网址。