ios - UITableView reloadData不执行任何操作(UITableView不为零)

我正在构建我的第一个真实应用程序，你们已经为您提供了最大的帮助，但是我一直在为tableView不更新而苦苦挣扎。我希望这里的人可以对此有所了解，并可能对我可能已经错过或不必要地复杂的其他事物提出任何想法。

目前，该应用程序应该执行以下操作:

用sqlite数据库中的数据填充表(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设置一个NSURLConnection，通过POST

与服务器进行通信

连接已接收到所有数据后，它将更新本地数据库

tableView数据源(它是NSMutableArray)已使用新的db数据

更新

tableview更新并列出数据库中的所有表[myTableView reloadData]称为

我仔细检查过的事情:tableview和委托(delegate)，数据源和 socket 之间的连接； tableView不为零；数据源本身已被正确更新；

一切工作到最后一点(7)。看来myTableView当时不是nil。有想法吗？并且请告诉我您是否需要查看更多我的代码。

我也看了一下beginUpdates和endUpdates方法，但在我看来，它们一次专注于一些更改以及用户交互。我只想根据用户选择重新加载整个表(即要根据当前用户登录名反射(reflect)整个其他SQL选择字符串)。还是有另一种甚至更好的方法呢？

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", sqlite3_errmsg(nil), 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 count]);

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

对于viewDidLoad，将调用tableView:numberOfRowsInSection:，并且dataSource不是nil，但是不会调用tableView:cellForRowAtIndexPath:，并且不会更新表。

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:

我试过使用断点检查值。

tableview内的断点:rowsinsection:

(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)

db更新之后，恰好在reloadData调用之前的断点:

(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,
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)

tableview:numberofrowsinsection中的断点:更新数据库并运行reloadData命令后:

(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,
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)

最佳答案

我看不到myTableView正在合成。
在执行reloadData时，还会调用tableView数据源方法吗？

如果不是，请仔细检查并确认myTableView委托(delegate)设置正确。
如果您已将Table正确连接到 Nib 并且有 socket ，则也可以通过设置以下代码在代码中进行设置，即在viewDidLoad方法中进行设置:

myTableView.delegate = self;

关于ios - UITableView reloadData不执行任何操作(UITableView不为零)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/12787821/