NSTimer：如何使用它到数据库

Question

我有一个数据库有5个记录，我需要使用计时器逐个显示屏幕上的记录。时间间隔应该是30秒。

- (NSMutableArray*) fnGetName 
{ 

DBCon *oDBCon = [[DBCon alloc] init]; 
[oDBCon fnInitializeDB]; 
NSMutableArray *arrDict = [[NSMutableArray alloc] init]; 
NSString *sQryName = [NSString stringWithFormat:@"SELECT * FROM tbl_names"]; 
sqlite3_stmt *selectstmt; 
if(sqlite3_prepare_v2(oDBCon.database, [sQryName UTF8String], -1, &selectstmt, NULL) == SQLITE_OK) 
{ 
     while(sqlite3_step(selectstmt) == SQLITE_ROW) { 
     oBlossom = [[Blossom alloc]initWithPrimaryKey:primaryKey database:oDBCon.database]; 
     oBlossom.psName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt,1)]; 
     NSLog(@"oBlossom.psName %@", oBlossom.psName); 
     oBlossom.psKeyword = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt,2)]; 
     NSLog(@"oBlossom.psKeyword %@", oBlossom.psKeyword); 
     [arrDict addObject:oBlossom]; 

} 

Answer 1

返回的arrDict，并使用定时器来更新UI

注：无效计时器，当你完成操作。否则它不会停止，并会导致崩溃。

-(void)disaplydisplayRecordsWithTimeInterval{ 

    NSMutableArray *myCollection = [self fnGetName]; 

    NSTimer timerWithTimeInterval:30.0 target:self selector:@selector(displayRecords:) userInfo:arrDict repeats:YES]; 

} 

- (void)displayRecords:(NSTimer*)theTimer { 

    NSMutableArray *myArrayCollection = (NSMutableArray *)theTimer.userInfo; 
    //your code here to displayRecords using myarrDict 
} 

- (NSMutableArray*) fnGetName { 

    DBCon *oDBCon = [[DBCon alloc] init]; 
    [oDBCon fnInitializeDB]; 
    NSMutableArray *arrDict = [[NSMutableArray alloc] init]; 
    NSString *sQryName = [NSString stringWithFormat:@"SELECT * FROM tbl_names"]; 
    sqlite3_stmt *selectstmt; 
    if(sqlite3_prepare_v2(oDBCon.database, [sQryName UTF8String], -1, &selectstmt, NULL) == SQLITE_OK) 
    { 
     while(sqlite3_step(selectstmt) == SQLITE_ROW) { 
      oBlossom = [[Blossom alloc]initWithPrimaryKey:primaryKey database:oDBCon.database]; 
      oBlossom.psName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt,1)]; 
      NSLog(@"oBlossom.psName %@", oBlossom.psName); 
      oBlossom.psKeyword = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt,2)]; 
      NSLog(@"oBlossom.psKeyword %@", oBlossom.psKeyword); 
      [arrDict addObject:oBlossom]; 

     } 

     //finilize database here 
    } 

    //close database here 

    return arrDict; 
}