setNeedsDisplay不会更改UITableView的中心

Question

Added a UITableView through IB . I'm trying to change the center of the UITableView programmatically:

- (IBAction)OnClickPrescribingDoctorButton:(id)sender
{
    [_prescribingDoctorTableView setNeedsDisplay];
    NSLog(@"check before %f",_prescribingDoctorTableView.center.y);

    _prescribingDoctorTableView.center = CGPointMake(50,200);

    NSLog(@"check after %f",_prescribingDoctorTableView.center.y);
}

LOG:

2014-04-21 13:40:18.898 SmartWatch[1833:70b] check before 788.000000
2014-04-21 13:40:18.898 SmartWatch[1833:70b] check after 200.000000

2014-04-21 13:40:20.075 SmartWatch[1833:70b] check before 788.000000
2014-04-21 13:40:20.075 SmartWatch[1833:70b] check after 200.000000

As you can see in the log, the Y-axis value of the UITableView changes but i don't see any effect visually or the UITableView being redrawn as i call setNeedsDisplay and i also don't understand why does Y-axis value value reverts back to 788 every time i call this code by clicking on a UIButton .

Answer 1

Try using [[_prescribingDoctorTableView superview] setNeedsLayout] instead of [_prescribingDoctorTableView setNeedsDisplay] to layout the subviews.

if this doesn't work, subclass your view and override the methods,

- (void)layoutSubviews (or) - (void)setFrame:(CGRect)frame

And debug by placing the break point in these methods so that you can come to know from where your frame being updated.