在导航控制器上按下时，UIView页面闪烁（仅第一次）

Question

I have the following view hierarchy in a UIView page:

2 UIButtons

1 ImageView

1 UILabel

1 UITableView - grouped style - contains only one cell (of type custom cell, created completely with code without any xib), the cell contains this view hierarchy:

ImageView

2 OHAttributedLabels [here's its gitHub page]

1 UILabel rotated vertically using CGAffineTransform method

I push the view controller of this view on a navigation controller using: pushViewController method, however, everything works fine except for the case of opening the application for the first time, when this view controller is pushed the view instantly flickers once (with some black strips on screen edges), when I navigate back to other views in the application, and then reopen this view, no flickering happens.

what is the cause of this flickering ?

thank you in advance.

ps the OHAttributedLabel is tested on other views in the application without any problems.

EDIT: the following code is from view1.m (the view im talking about in the question above):

 - (void)viewDidLoad
 {
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.

UIImage *backgroundImage = [UIImage imageNamed: @"bg1.png"];
UIImageView *backGroundImageView = [[[UIImageView alloc] initWithImage: backgroundImage] autorelease];
backGroundImageView.frame = CGRectMake(0,0,320,411);



[self.view addSubview: backGroundImageView];
[self.view sendSubviewToBack: backGroundImageView];

self.gsTableView.layer.cornerRadius = 10; // to make a the corner of the table view rounded

self.gsParagraphs = [NSArray arrayWithObjects:
                          NSLocalizedString(@"this is a test string this is a test string this is a test string this is a test string this is a test string this is a test string this is a test string this is a test string this is a test string" , @"test string1"), 
                      NSLocalizedString(@"this is another test string this is another test string this is another test string this is another test string this is another test string this is another test string" , @"test string2"),

                          nil];

     }

and the following code is for cellForRowAtIndexPath method in view1.m file:

      - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
          {
          NSString *MyIdentifier = [NSString stringWithFormat:@"MyIdentifier %i", indexPath.row];
          CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:MyIdentifier];

if (cell == nil) {
    cell = [[[CustomCell alloc] initWithFrame:CGRectZero reuseIdentifier:MyIdentifier] autorelease];

} 

        cell.imageView.image = [UIImage imageNamed: @"gs_1.jpg"];
        cell.imageView.layer.masksToBounds = YES;
        cell.imageView.layer.cornerRadius = 5.0;
       // cell.textLabel.text = [self.gsParagraphs objectAtIndex:0]; //it will become blurry

        //note: the attributed label is used to easily apply justified alignment and many other options
        NSMutableAttributedString* cellBody1 = [NSMutableAttributedString attributedStringWithString:[self.gsParagraphs             objectAtIndex:0]];
        [cellBody1 setTextAlignment:UITextAlignmentJustify lineBreakMode: UILineBreakModeWordWrap];
        cell.secondTextLabel.attributedText = cellBody1;

        NSMutableAttributedString* cellBody2 = [NSMutableAttributedString attributedStringWithString:[self.gsParagraphs objectAtIndex:1]];
      [cellBody2 setTextAlignment:UITextAlignmentJustify lineBreakMode: UILineBreakModeWordWrap];
      cell.thirdTextLabel.attributedText = cellBody2;

       // cell.cellLabelTextYOffset = 10; this is necessary only for the original text label
        cell.cellTitle.text = NSLocalizedString(@"Test Title", @"Test Title");
        cell.cellTitleLabelWidth = 170;

       return cell;

       }

there is no code for viewDidAppear method

Answer 1

Its a little unclear why you suspect your table view controller. Is the flicker inside table's bounds?

Some suspects:

• Your XIB may define one view with a black background that is covered by another view with your expected color.
• a resize event can happen if the view is the wrong size by a few pixels.
• a rotate event could happen when the objects are first instantiated. I have been told of a case where the view was getting a rotate from and to the same orientation which left black bars. (Not sure how that happened, but it was logged from within the delegate methods.)

If you create all the delegate methods for both the view controller and table delegates, which ones are called in what order?

I don't know if it still works, but I have used a single white button in place of a one-cell grouped table. If you never plan to add another cell, there is little need to use an entire table.