Customize navigation bar with title view

Swift 3/4

You may set i.e. UILabel as a titleView. Call it in viewDidLoad():

private func setNavigationTitle(_ title: String) {
    navigationItem.title = nil // clear the default title
    let titleLabel = UILabel() // you don't need to specify a frame, it will be centred in the navbar
    titleLabel.font = ...
    titleLabel.textColor = ...
    titleLabel.text = title
    titleLabel.backgroundColor = .clear
    navigationItem.titleView = titleLabel
    navigationTitleView = titleLabel // you may create a property if you want to manipulate the title view later
}

Note navigationItem.title = nil, otherwise title may override titleView.

Replace

[self.navigationController.navigationItem.titleView addSubview:testView];

to

self.navigationItem.titleView = testView;

Edit:

Note: You cannot add subviews to titleView cause it's default value is nil, you need to set a new view as the titleView.

This works. Give frame at the time of initialisation

UIView *iv = [[UIView alloc] initWithFrame:CGRectMake(0,0,32,32)];
[iv setBackgroundColor:[UIColor whiteColor]];
self.navigationItem.titleView = iv;

If you want to just customize the title for one view controller you can use

UILabel *lblTitle = [[UILabel alloc] init];
lblTitle.text = @"Diga-nos o motivo";
lblTitle.backgroundColor = [UIColor clearColor];
lblTitle.textColor = [UIColor colorWithRed:77.0/255.0 green:77.0/255.0 blue:77.0/255.0 alpha:1.0];
lblTitle.shadowColor = [UIColor whiteColor];
lblTitle.shadowOffset = CGSizeMake(0, 1);
lblTitle.font = [UIFont fontWithName:@"HelveticaNeue-Bold" size:18.0];
[lblTitle sizeToFit];

self.navigationItem.titleView = lblTitle;

or if you want to customize for all view controllers use

[[UINavigationBar appearance] setTitleTextAttributes:
    [NSDictionary dictionaryWithObjectsAndKeys:
        [UIColor colorWithRed:255.0/255.0 green:255.0/255.0 blue:255.0/255.0 alpha:1.0], 
        UITextAttributeTextColor, 
        [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.8], 
        UITextAttributeTextShadowColor, 
        [NSValue valueWithUIOffset:UIOffsetMake(0, -1)], 
        UITextAttributeTextShadowOffset, 
        [UIFont fontWithName:@"Arial-Bold" size:10.0], 
        UITextAttributeFont, 
        nil]];