View flashes when popToRootViewController

Question

I am having a problem with popToRootViewController. I have a root view A and a table view B. And when a row is selected in the table view I pass a string back to the root view and depending on the string. I change the title of buttons on A.

I have made a very simple version of this and put it on gitHub at this link: https://github.com/spennyf/didSelect_test. I am doing this because it is very hard to explain until you actually run this on your phone of the simulator. And see the flash. I don't know why it is happening or how to fix it. Any help would be greatly appreciated I will also post most of the code below, but if you could see the flash for yourself I think it would help explain the problem. Heres the code:

viewControllerA.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@property (strong, nonatomic) IBOutlet UIButton *btn1;

@property (strong, nonatomic) IBOutlet UIButton *btn2;

@property (strong, nonatomic) IBOutlet NSString *object;

@end

viewControllerA.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

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

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)viewWillAppear:(BOOL)animated {
    NSLog(@"object: %@", _object);
    if ([_object isEqualToString:@"object1"]) {
        [_btn1 setTitle:@"new1" forState:UIControlStateNormal];
    }
    if ([_object isEqualToString:@"object2"]) {

        [_btn2 setTitle:@"new2" forState:UIControlStateNormal];
    }

}

@end

tableviewB.m

#import "TableViewController.h"
#import "ViewController.h"

@interface TableViewController () {
    NSMutableArray *_objects;

}


@end

@implementation TableViewController


- (void)viewDidLoad
{
    [super viewDidLoad];

    _objects = [[NSMutableArray alloc] init];

    NSDictionary *obj1 = [[NSDictionary alloc] initWithObjectsAndKeys:@"object1", @"title", nil];
    NSDictionary *obj2 = [[NSDictionary alloc] initWithObjectsAndKeys:@"object2", @"title", nil];
    // NSDictionary *obj3 = [[NSDictionary alloc] initWithObjectsAndKeys:@"rpi", @"title", nil];

    [_objects addObject:obj1];
    [_objects addObject:obj2];



}



#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // Return the number of rows in the section.
    return _objects.count;

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";


    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
        cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    }

    //NSLog(@"%@", _objects);
    cell.textLabel.text = [[_objects objectAtIndex:indexPath.row] objectForKey:@"title"];

    return cell;
}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    ViewController *myController = (ViewController *)[self.navigationController.viewControllers objectAtIndex:0];
    myController.object = [[_objects objectAtIndex:indexPath.row] objectForKey:@"title"];
    [self.navigationController popToRootViewControllerAnimated:YES];

}


@end

Again thanks for the help.

Answer 1

There is no problem with your code. It is intended behavior for UIButtons of type UIButtonTypeSystem to flash when its title is changed.

A simple workaround is to set the type of your buttons to UIButtonTypeCustom.

Edit: You can change the type of the button in Interface Builder: