Question

我是Objective C新手（背景包括perl / php / VB ......非面向对象）。我正在尝试学习Objective C和xcode，并致力于将数据作为测试用例的项目。它使用故事板。

我有一个数据库类，一个单项项目，一个多项项目和一个视图控制器。我删除了默认场景并添加了一个表视图控制器，并选择了控制器作为类。我可以在NSlog中获取要转储的数据，但是我坚持让它在Table View上显示。这是我所拥有的（省略了单项h和m以及AppDelegate文件）：

CarbDatabase.h：

#import <Foundation/Foundation.h>
#import "/usr/include/sqlite3.h"


@interface CarbDatabase : NSObject {
    sqlite3 *_database;
}


+ (CarbDatabase*)database;
- (NSArray *)FoodItems;

@end

CarbDatabase.m：

#import "FoodItem.h"
#import "CarbDatabase.h"

@implementation CarbDatabase

static CarbDatabase *_database;

+ (CarbDatabase*)database {
    if (_database == nil) {
        _database = [[CarbDatabase alloc] init];
    }
    return _database;
}

- (id)init {
   if ((self = [super init])) {
    NSString *sqLiteDb = [[NSBundle mainBundle] pathForResource:@"food" ofType:@"sqlite3"];

       if (sqlite3_open([sqLiteDb UTF8String], &_database) != SQLITE_OK) {
        NSLog(@"Failed to open database!");
            }
        }
    return self;
   }

- (NSArray *)FoodItems {

NSMutableArray *retval = [[NSMutableArray alloc] init];
NSString *query = @"SELECT ID, LongDesc, ShortDesc, Carb, Sugar, lipid, GrmWt1, GrmWtDesc1, GrmWt2, GrmWtDesc2 FROM food ORDER BY LongDesc";

sqlite3_stmt *statement;
if (sqlite3_prepare_v2(_database, [query UTF8String], -1, &statement, nil)
    == SQLITE_OK) {
    while (sqlite3_step(statement) == SQLITE_ROW) {
        int uniqueID = sqlite3_column_int(statement, 0);
        char *LongDescChars = (char *) sqlite3_column_text(statement, 1);
        char *ShortDescChars = (char *) sqlite3_column_text(statement, 2);
        int Carb = sqlite3_column_int(statement, 3);
        int Sugar = sqlite3_column_int(statement, 4);
        int Lipid = sqlite3_column_int(statement, 5);
        int GrmWt1 = sqlite3_column_int(statement, 6);
        char *GrmWtDesc1Chars = (char *) sqlite3_column_text(statement, 7);
        int GrmWt2 = sqlite3_column_int(statement, 8);
        char *GrmWtDesc2Chars = (char *) sqlite3_column_text(statement, 9);
        NSString *LongDesc = [[NSString alloc] initWithUTF8String:LongDescChars];
        NSString *ShortDesc = [[NSString alloc] initWithUTF8String:ShortDescChars];
        NSString *GrmWtDesc1 = [[NSString alloc] initWithUTF8String:GrmWtDesc1Chars];
        NSString *GrmWtDesc2 = [[NSString alloc] initWithUTF8String:GrmWtDesc2Chars];

            FoodItem *info = [[FoodItem alloc] initWithuniqueID:uniqueID LongDesc:LongDesc ShortDesc:ShortDesc Carb:Carb Sugar:Sugar Lipid:Lipid GrmWt1:GrmWt1 GrmWtDesc1:GrmWtDesc1 GrmWt2:GrmWt2 GrmWtDesc2:GrmWtDesc2];

            [retval addObject:info];
        }
        sqlite3_finalize(statement);
    }
    else
    {
        NSLog (@"statement failed");
    }
    return retval;
}

@end

或者Controller.h：

#import <UIKit/UIKit.h>

@interface CarbViewController : UITableViewController

@property (nonatomic, retain) NSArray *FoodItems;

@end

Controller.m或者：

#import "CarbViewController.h"
#import "CarbDatabase.h"
#import "FoodItem.h"
#import "/usr/include/sqlite3.h"

@interface CarbViewController ()

@end

@implementation CarbViewController


- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{

    self.FoodItems = [CarbDatabase database].FoodItems;
    self.title = @"Food Items %d",[_FoodItems count];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 0;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

    return [_FoodItems count];

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

    static NSString *CellIdentifier = @"FoodItem";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
                             if (cell == nil) {
                                 cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
                             }

    // Configure the cell...
    int rowcount = indexPath.row;
    FoodItem *info = [_FoodItems objectAtIndex:indexPath.row];
    cell.textLabel.text = info.ShortDesc;
    cell.detailTextLabel.text = [NSString stringWithFormat:@"%d Carbs per 100 Grams", info.Carb];

    return cell;
}

/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the specified item to be editable.
    return YES;
}
*/

/*
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
    }   
    else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }   
}
*/

/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
}
*/

/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the item to be re-orderable.
    return YES;
}
*/

#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];
     */
}

@end

Answer 1

我不知道是否还有更多问题，但是 numberOfSectionsInTableView:应返回1，而不是0（否则为表视图永远都是空的。）

或者，不要实现该方法，因为默认值为1。

使用xcode在Table View中显示sqlite3结果

1 个答案: