How to fire hightlight effect on UIBarButtonItem

问题:

When you tap on a UIBarButtonItem in a UIToolbar, there is a white glow effect.

Is there a possibility to fire an event to show this effect?

I don't want to press the button. Only the effect should be displayed. I want to visualize to the user, that there is new content behind this button.

Thanks for your help!

回答1:

The following method assumes you are using the toolbarItems property of a navigation controller and that the button you want to highlight is the last item in that array. You can apply it to any toolbar, of course, and pick a different array index if necessary.

Right now this is not exactly perfect, because the animation moves the new button from the lower left of the screen. However, I think that can be turned off with a little effort.

Note that I used PeakJi's image.

I hope this works for you.

Enjoy,

Damien

- (void)highlightButton {
    NSArray *originalFooterItems = self.toolbarItems;
    NSMutableArray *footerItems = [originalFooterItems mutableCopy];
    [footerItems removeLastObject];

    NSString* pathToImageFile = [[NSBundle mainBundle] pathForResource:@"white_glow" ofType:@"png"];
    UIImage* anImage = [UIImage imageWithContentsOfFile:pathToImageFile];
    UIImageView *imageView = [[UIImageView alloc] initWithImage:anImage];
    imageView.frame = CGRectMake(0, 0, 40, 40);

    UIBarButtonItem *flashImage = [[UIBarButtonItem alloc] initWithCustomView:imageView];
    [footerItems addObject:flashImage];

    [UIView animateWithDuration:0.3
                          delay: 0.0
                        options: UIViewAnimationOptionCurveEaseOut
                     animations:^{
                         self.toolbarItems = footerItems;                     }
                     completion:^(BOOL finished){
                         [UIView animateWithDuration:.3
                                               delay: 0.0
                                             options:UIViewAnimationOptionCurveEaseIn
                                          animations:^{
                                              self.toolbarItems = originalFooterItems;
                                          }
                                          completion:nil];
                     }];
}

回答2:

Heres the "highlight.png", I'm not kidding! (Though you may not seeing it on a white background.)

回答3:

For Bar items

 [(UIButton *)[[toolbarItems objectAtIndex:1] customView] setImage:[UIImage imageNamed:@"highlight.png"] forState:UIControlStateNormal];

In General - Assuming you have a button

UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:self 
           action:@selector(someFunction:)
 forControlEvents:UIControlEventTouchDown];
[button setTitle:@"Click here" forState:UIControlStateNormal];
button.frame = CGRectMake(0.0, 0.0, 100.0, 40.0);
[self.view addSubview:button];

you can at any given point, programmatically call this function:

[button setTitle:@"Look Here" forState:UIControlStateNormal];

or if you like to have an highlight image

btnImage = [UIImage imageNamed:@"highlight.png"];
[button setImage:btnImage forState:UIControlStateNormal];

A very simple alternative:

That said , you can also set the button like this:

- (void)highlightButton:(UIButton *)button { 
    [button setHighlighted:YES];
}

回答4:

You can try to recreate a new bar button item with different style, and then reassign it back. My experiment was:

In viewDidLoad:

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIBarButtonItem *rightBtn = [[UIBarButtonItem alloc] initWithTitle:@"Custom"
                                                                 style:UIBarButtonItemStylePlain
                                                                target:self
                                                                action:nil];
    self.navigationItem.rightBarButtonItem = rightBtn;
    [rightBtn release];

    [self performSelector:@selector(highlight)
               withObject:nil
               afterDelay:2.0];
}

And in method highlight:

- (void) highlight{
    UIBarButtonItem *rightBtn = [[UIBarButtonItem alloc] initWithTitle:@"Custom"
                                                                 style:UIBarButtonItemStyleDone
                                                                target:self
                                                                action:nil];
    self.navigationItem.rightBarButtonItem = rightBtn;
    [rightBtn release];
}

Your implementation might be different than mine, but as long as you are fine with reassigning the bar button, I think it'll work as expected. Good luck :)

回答5:

If you have a category:

#define HIGHLIGHT_TIME 0.5f

@interface UIButton (Highlight)
- (void)highlight;
@end

@implementation UIButton (Highlight)

- (void)highlight {
    UIButton *overlayButton = [UIButton buttonWithType:UIButtonTypeCustom];
    overlayButton.frame = self.frame;
    overlayButton.showsTouchWhenHighlighted = YES;
    [self.superview addSubview:overlayButton];
    overlayButton.highlighted = YES;
    [self performSelector:@selector(hideOverlayButton:) withObject:overlayButton afterDelay:HIGHLIGHT_TIME];
}

- (void)hideOverlayButton:(UIButton *)overlayButton {
    overlayButton.highlighted = NO;
    [overlayButton removeFromSuperview];
}

@end

Then you need code like this…

UIBarButtonItem *addButton = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(insertNewObject:)] autorelease];
self.navigationItem.rightBarButtonItem = addButton;
[self.navigationController.navigationBar.subviews.lastObject performSelector:@selector(highlight) withObject:nil afterDelay:2];

…to highlight the button in the navigation bar after 2 seconds.

回答6:

A simple ay is to init your UIBarButtonItem with a CustomView (UIBUtton)

UIButton *favButton = [UIButton buttonWithType:UIButtonTypeCustom];
[favButton setFrame:CGRectMake(0.0, 100.0, 50.0, 30.0)];
[favButton setBackgroundImage:[UIImage imageNamed:@"bouton_black_normal.png"] 
           forState:UIControlStateNormal];
[favButton setBackgroundImage:[UIImage imageNamed:@"bouton_black_hightlight.png"] 
           forState:UIControlStateHighlighted];
[favButton setTitle:@"Add" forState:UIControlStateNormal];
[favButton setTitle:@"Add" forState:UIControlStateHighlighted];
[favButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
[favButton setTitleColor:[UIColor whiteColor] forState:UIControlStateHighlighted];
[[favButton titleLabel] setFont:[UIFont boldSystemFontOfSize:13]];
[favButton addTarget:self action:@selector(doSomething)
    forControlEvents:UIControlEventTouchUpInside];

UIBarButtonItem *button = [[UIBarButtonItem alloc] initWithCustomView:favButton];