ios – UITableView reloadData什么都不做(UITableView不是nil)

我正在构建我的第一个真正的应用程序,你们已经是最有帮助的,但我一直在努力与tableView不更新.我希望这里的某个人可以对此有所了解,并且可能想出任何关于我可能错过或完成不必要的其他事情的想法.

目前,应用应该执行以下操作：

>使用来自sqlite db的数据填充表(基本上只列出所有表)
>用户按下按钮(触发fetchData方法)
>(void)fetchData将本地数据库与服务器数据库校验和进行比较
>(void)fetchData设置NSURLConnection,通过POST与服务器通信
>当连接收到所有数据时,它会更新本地数据库
>使用新的db数据更新tableView dataSource(NSMutableArray)
> tableview更新并列出数据库中的所有表[myTableView reloadData]被调用

我经过双重检查的事情：tableview和delegate,datasource和outlet之间的连接; tableView不是零;数据源本身已经准确更新;

一切都达到了最后一点(7).似乎myTableView当时并不是零.想法？如果您需要查看更多我的代码,请告诉我.

我也看了一下beginUpdates和endUpdates的方法,但在我看来,他们一度关注一些变化和用户交互性.我想根据用户选择重新加载整个表(即希望根据当前用户登录反映整个其他SQL选择字符串).或者还有另一种更好的方法吗？

提前致谢！

这是一段相当不错的代码：

#import "FirstViewController.h"
@interface FirstViewController ()
@end

@implementation FirstViewController
#import "FirstViewController.h"

@synthesize myTextView,myTableViewDataSource,myFetchedData,resultat,tablesAndChecks,tablesArr,checksArr,tablesToRequest,receivedData,receivedDataString,SQL,sqlStatementsArr,failedSqlStatementsArr,failedSqlStatementsCodeArr,dbloop1;



#pragma mark Table view methods
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    NSLog(@"Konfigurerar tableView"); //swedish for "Configuring tableView"
    if(myTableView.dataSource==nil){
        NSLog(@"datasource = nil");
    }else{
        NSLog(@"datasource != nil"); //This prints in log
    }
    NSLog(@"%d",[myTableViewDataSource count]); //prints "19" in log

    return [myTableViewDataSource count];
}

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    NSLog(@"calling cellForRowAtIndexPath"); //This does NOT print in log

    static NSString *CellIdentifier = @"myCell";

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

    // Set up the cell...
    cell.textLabel.font = [UIFont fontWithName:@"Helvetica" size:15];
    cell.textLabel.text = [NSString  stringWithFormat:@"Tabell %d: %@",[indexPath row],[myTableViewDataSource objectAtIndex:[indexPath row]]];

    return cell;
}



- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"connection did finish loading");

    //...
    //script that receives a long SQL-string from the server
    //and then updates the database with it goes here    
    //...

    //Ok,so now the database has updated correctly,and it's time 
    //to update the tableview so that it reflects the new data.
    //
    //Get data from database...
    NSMutableArray * tempArray = [[NSMutableArray alloc] initWithCapacity:0];

    if (sqlite3_open(dbpath,&contactDB) == SQLITE_OK)
    {
        NSLog(@"Databasen öppnad");
        NSString *beginSQL = [NSString stringWithFormat: @"SELECT name FROM sqlite_master WHERE type='table' ORDER BY name;"];
        const char *begin_stmt = [beginSQL UTF8String];
        sqlite3_prepare_v2(contactDB,begin_stmt,-1,&statement,NULL);
        while(sqlite3_step(statement) == SQLITE_ROW) {
            char *col1 = (char *)sqlite3_column_text(statement,0);
            if (col1 !=NULL){
                [tempArray addObject:[NSString stringWithUTF8String: col1]];
            }
        }
        if (sqlite3_step(statement) == SQLITE_DONE)
        {
            NSLog(@"#####%s;   Done: %@",sqlite3_errmsg(nil),beginSQL);
        } else {
            NSLog(@"#####%s;   Error with string: %@; Errcode: %d Errmsg: %s",beginSQL,sqlite3_errcode(contactDB),sqlite3_errmsg(nil));
        }

        NSLog(@"%d",sqlite3_finalize(statement));
        sqlite3_close(contactDB);

        //update the datasource to the values of tempArray
        myTableViewDataSource = tempArray;

        //Some logging to see that the updated data is in the array... (which it is)
        NSLog(@"myTableViewDataSource count: %d",[myTableViewDataSource count]);

        for (i=0; i<[myTableViewDataSource count]; i++) {
            NSLog(@"%@",[myTableViewDataSource objectAtIndex:i]);
        }
    }

    //Finally,check so that myTableView isn't nil and can receive messages
    if(myTableView == nil){
        NSLog(@"NILCHECK mytableview is nil!");
    }else{
        NSLog(@"NILCHECK mytableview is NOT nil!"); //This is printed out to the log
    }

    //Reload data -> nothing happens...
    [myTableView reloadData];
}


- (void)fetchData
{
    //function that gets current checksums for all db tables on the server,compares them to the local database
    //and then requests an SQL-string from the server to update the tables that needs it.
    //I don't think this is relevant for my problem,and it runs fine anyways.

    //The last thing it does is setting up a NSURLConnection to communicate with 
    //the server (sending which tables to request via POST and then getting the SQL-string as the server response)

        NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:request delegate:self];
        if (theConnection) {
            //receivedData = [NSMutableData data];
            NSLog(@"ReceivedData är: %d",[receivedData length]);
        } else {
            NSLog(@"Connection Failed!");
        }

        //All done here,now the ReceivedData method takes over

    }
}

更新：

这是我的viewDidLoad方法：

- (void)viewDidLoad
{
    //creates database and fills "tempArray" with data

        NSLog(@"%d",sqlite3_finalize(statement));
        sqlite3_close(contactDB);

        myTableViewDataSource = tempArray;
        NSLog(@"myTableViewDataSource count: %d",[myTableViewDataSource objectAtIndex:i]);
        }

    }

    myTableView = [[UITableView alloc] initWithFrame:self.view.frame style:UITableViewStylePlain];
    myTableView.delegate = self;   //Added this after comment (1)
    myTableView.dataSource = self; //Added this after comment (2)
}

更新：
添加后：

myTableView.delegate = self;
myTableView.dataSource = self;

to viewDidLoad,tableView：numberOfRowsInSection：被调用,而dataSource不是nil,但是没有调用tableView：cellForRowAtIndexPath：,并且表没有被更新.

更新2：
这是我的头文件：

//
//  FirstViewController.h
//  OHBSYS Storyboards
//
//  Created by David Forsberg on 2012-09-25.
//  Copyright (c) 2012 David Forsberg. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <sqlite3.h>

@interface FirstViewController : UIViewController <UITableViewDataSource,UITableViewDelegate>{
    NSString *databasePath;
    sqlite3 *contactDB;

    UITextView *myTextView;
    UITableView *myTableView;

    NSMutableArray *myTableViewDataSource;

    NSMutableString * tableRowCount;
    NSMutableArray * dbloop1;

    //And a bunch of other variables here
}

@property (retain,nonatomic) IBOutlet UITextView *myTextView;
@property (nonatomic,retain) IBOutlet UITableView *myTableView;
@property (nonatomic,retain) IBOutlet NSMutableArray *myTableViewDataSource;

- (IBAction) fetchData;

@property (nonatomic) NSString * tableRowCount;
@property (nonatomic,retain) NSMutableArray * dbloop1;

//A bunch of other properties here as well

@end

更新3：

我已经尝试使用断点检查值.

tableview内的断点：numberofrowsinsection：

(lldb) po self.myTableView
(UITableView *) $0 = 0x0d13ca00 <UITableView: 0xd13ca00; frame = (0 20; 768 1004); clipsToBounds = YES; layer = <CALayer: 0x2a3d30>; contentOffset: {0,0}>
(lldb) po self.myTableView.delegate
(objc_object *) $1 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableView.dataSource
(objc_object *) $2 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableViewDataSource
(NSMutableArray *) $3 = 0x0029fb20 <__NSArrayM 0x29fb20>(
CONTACTS,sqlite_sequence
)

(lldb)

数据库更新后的断点,就在调用reloadData之前：

(lldb) po self.myTableView
(UITableView *) $4 = 0x0d13ca00 <UITableView: 0xd13ca00; frame = (0 20; 768 1004); clipsToBounds = YES; layer = <CALayer: 0x2a3d30>; contentOffset: {0,0}>
(lldb) po self.myTableView.delegate
(objc_object *) $5 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableView.dataSource
(objc_object *) $6 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableView.dataSource //(accidentally hit that twice)
(objc_object *) $7 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableViewDataSource
(NSMutableArray *) $8 = 0x0ce6baa0 <__NSArrayM 0xce6baa0>(
CONTACTS,meta_tablechecksums,prot_multicoltest,prot_multicoltest_4,prot_multicoltest_4_desc,prot_multicoltest_desc,sqlite_sequence,superadmin_filefolders,superadmin_files,superadmin_imagefolders,superadmin_images,sys_customers,sys_fieldlooks,sys_fieldtypes,sys_formtables,sys_pages,sys_subpages,sys_userroles,sys_users
)

(lldb)

断点AT reloadData行：

(lldb) po self.myTableView
(UITableView *) $9 = 0x0d13ca00 <UITableView: 0xd13ca00; frame = (0 20; 768 1004); clipsToBounds = YES; layer = <CALayer: 0x2a3d30>; contentOffset: {0,0}>
(lldb) po self.myTableView.delegate
(objc_object *) $10 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableView.dataSource
(objc_object *) $11 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableViewDataSource
(NSMutableArray *) $12 = 0x0ce6baa0 <__NSArrayM 0xce6baa0>(
CONTACTS,sys_users
)

(lldb)

tableview中的断点：numberofrowsinsection：在更新db并运行reloadData命令之后：

(lldb) po self.myTableView
(UITableView *) $13 = 0x0d13ca00 <UITableView: 0xd13ca00; frame = (0 20; 768 1004); clipsToBounds = YES; layer = <CALayer: 0x2a3d30>; contentOffset: {0,0}>
(lldb) po self.myTableView.delegate
(objc_object *) $14 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableView.dataSource
(objc_object *) $15 = 0x0ce99500 <FirstViewController: 0xce99500>
(lldb) po self.myTableViewDataSource
(NSMutableArray *) $16 = 0x0ce6baa0 <__NSArrayM 0xce6baa0>(
CONTACTS,sys_users
)

(lldb)

解决方法

我没有看到myTableView被合成.
在执行reloadData时,还调用了tableView数据源方法吗？

如果没有,请仔细检查并验证myTableView委托是否设置正确.
如果您已正确地将表连接到笔尖并且您有一个插座,您也可以在代码中设置它,即在viewDidLoad方法中,通过设置：

myTableView.delegate = self;

ios – UITableView reloadData什么都不做(UITableView不是nil)

解决方法

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