加载ViewController之前先加载ViewController

Question

In my ViewController I load my TableView data from a mySQL server online. When I press the button that load the ViewController, it takes time before loading the ViewController.

Although my data is being called after viewDidLoad method ..

- (void)viewDidLoad {
    [super viewDidLoad];

    MyArray = [[NSMutableArray alloc]initWithCapacity:10];
    MyData = [NSUserDefaults standardUserDefaults];

    MySqlDataBase *mySql = [[MySqlDataBase alloc]init];
    MyArray = [mySql doQueryGetArray:@"SELECT * FROM member" ForDataBaseWithName:@"Estifta"];
    NSLog(@"%@",[[MyArray objectAtIndex:0]objectForKey:@"text"]);
    [_myTabeView reloadData];
}

Answer 1

viewDidLoad is called when your view is loaded into the memory but before the view is displayed on screen. Your code in viewDidLoad runs on the mainThread (UIThread) and therefore slows the display of the view on screen.

As solution you could dispatch the long running parts on a background queue (using dispatch_async) and afterwards reload the tableview on the main thread.

    __weak typeof(self) weakSelf = self;
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
MySqlDataBase *mySql = [[MySqlDataBase alloc]init];        
MyArray = [mySql doQueryGetArray:@"SELECT * FROM member" ForDataBaseWithName:@"Estifta"];
        dispatch_async(dispatch_get_main_queue(), ^{
            [weakSelf.myTabeView reloadData];
        });
    });