Question

我是iphone开发的新手（xcode中的第3天），我在从NSMutableArray填充tableview时遇到了麻烦。我正在使用this教程作为我的指南，我的实现略有修改，因此我可以在pageControl中显示该表。我确定我的数组是用数据填充的，但在填充数组之后它不会显示在表中。我尝试过使用重载数据方法，但这导致我的应用程序崩溃。任何帮助是极大的赞赏。

我的代码

标题

#import <UIKit/UIKit.h>

@interface TwitterView : UIViewController <UITableViewDelegate>{

NSMutableArray *tweets;  
UITableView *twitterTable;    

} 

@property (nonatomic, retain) NSMutableArray *tweets;  
@property (nonatomic, retain) IBOutlet UITableView *twitterTable;
@end

实施

#import "TwitterView.h"
#import "Tweet.h"


//JSON 
@interface NSDictionary(JSONCategories)
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress;
-(NSData*)toJSON;
@end

@implementation NSDictionary(JSONCategories)
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress
{
    NSData* data = [NSData dataWithContentsOfURL: [NSURL URLWithString: urlAddress] ];
__autoreleasing NSError* error = nil;
id result = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions     error:&error];
if (error != nil) return nil;
return result;
}

-(NSData*)toJSON
{
NSError* error = nil;
id result = [NSJSONSerialization dataWithJSONObject:self options:kNilOptions error:&error];
if (error != nil) return nil;
return result;    
}
@end

@implementation TwitterView

@synthesize tweets;
@synthesize twitterTable;

#pragma mark -
#pragma mark View lifecycle


- (void)viewDidLoad {
  [super viewDidLoad];

tweets = [[NSMutableArray alloc]init];
//JSON CODE
dispatch_async(kBgQueue, ^{
    NSData* data = [NSData dataWithContentsOfURL: twitterURL];
    [self performSelectorOnMainThread:@selector(fetchedData:) withObject:data waitUntilDone:YES];
});

}

#pragma mark -
#pragma mark Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return 1;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
return [tweets count];
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 80;
}


// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

static NSString *CellIdentifier = @"Cell";

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}

  // Configure the cell...

NSDictionary *aTweet = [tweets objectAtIndex:[indexPath row]];

    cell.textLabel.text = [aTweet objectForKey:@"text"];
cell.textLabel.adjustsFontSizeToFitWidth = YES;
cell.textLabel.font = [UIFont systemFontOfSize:12];
cell.textLabel.minimumFontSize = 10;
cell.textLabel.numberOfLines = 4;
cell.textLabel.lineBreakMode = UILineBreakModeWordWrap;

cell.detailTextLabel.text = [aTweet objectForKey:@"from_user"];

NSURL *url = [NSURL URLWithString:[aTweet objectForKey:@"profile_image_url"]];
NSData *data = [NSData dataWithContentsOfURL:url];
cell.imageView.image = [UIImage imageWithData:data];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
return cell;
 }

#pragma mark -
#pragma mark Table view delegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
 // Navigation logic may go here. Create and push another view controller.
/*
 <#DetailViewController#> *detailViewController = [[<#DetailViewController#> alloc]   initWithNibName:@"<#Nib name#>" bundle:nil];
 // ...
 // Pass the selected object to the new view controller.
 [self.navigationController pushViewController:detailViewController animated:YES];
 [detailViewController release];
 */
}


#pragma mark -
#pragma mark Memory management

- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];

// Relinquish ownership any cached data, images, etc that aren't in use.
}

- (void)dealloc {
[tweets release];
[twitterTable release];
[super dealloc];
}


//JSON CODE
- (void)fetchedData:(NSData *)responseData {
//parse out the json data
NSError* error;
NSDictionary* json = [NSJSONSerialization JSONObjectWithData:responseData //1
                                                     options:kNilOptions 
                                                       error:&error];


tweets = [json objectForKey:@"results"];
NSLog(@"The Tweets %@", tweets);    

//[twitterTable reloadData];<--Cause app to crash


}

@end

Answer 1

tweets = [json objectForKey:@"results"];

在这里，您将自动释放的值设置为推文ivar，并在您尝试将其用于表格视图时将其解除分配。要解决此问题，请不要为实例变量赋值，而是使用属性（它还会阻止存储在tweets变量中的先前值泄漏）：

self.tweets = [json objectForKey:@"results"];

另外考虑使用ARC（自动引用计数），它可以帮助您避免很多内存管理问题。

为什么不是UITableView从数组填充

1 个答案: