问如何在按下按钮时预先形成动作？
EN

Stack Overflow用户

提问于 2014-06-17 07:47:36

回答 3查看 369关注 0票数 1

我有一个按钮，当按钮被按到@"PRESSED"时，我需要更改标签，如果它被释放了，我需要将它更改为@"LET GO"。我找到了很多答案，但我不知道如何在Xcode 5中实现它们。

您可以在touchDownInside上启动您的操作，并在touchUpInside操作上停止它--您可以将它们连接到IB中。

或

将目标添加到控件状态( UIControlEventTouchDown和UIControlEventTouchUpInside或UIControlEventTouchUpOutside )的按钮中

甚至是

Add a dispatch source iVar to your controller...

dispatch_source_t     _timer;
Then, in your touchDown action, create the timer that fires every so many seconds. You will do your repeating work in there.

If all your work happens in UI, then set queue to be

dispatch_queue_t queue = dispatch_get_main_queue();
and then the timer will run on the main thread.

- (IBAction)touchDown:(id)sender {
    if (!_timer) {
        dispatch_queue_t queue = dispatch_get_global_queue(
            DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
        _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
        // This is the number of seconds between each firing of the timer
        float timeoutInSeconds = 0.25;
        dispatch_source_set_timer(
            _timer,
            dispatch_time(DISPATCH_TIME_NOW, timeoutInSeconds * NSEC_PER_SEC),
            timeoutInSeconds * NSEC_PER_SEC,
            0.10 * NSEC_PER_SEC);
        dispatch_source_set_event_handler(_timer, ^{
            // ***** LOOK HERE *****
            // This block will execute every time the timer fires.
            // Do any non-UI related work here so as not to block the main thread
            dispatch_async(dispatch_get_main_queue(), ^{
                // Do UI work on main thread
                NSLog(@"Look, Mom, I'm doing some work");
            });
        });
    }

    dispatch_resume(_timer);
}
Now, make sure to register for both touch-up-inside and touch-up-outside

- (IBAction)touchUp:(id)sender {
    if (_timer) {
        dispatch_suspend(_timer);
    }
}
Make sure you destroy the timer

- (void)dealloc {
    if (_timer) {
        dispatch_source_cancel(_timer);
        dispatch_release(_timer);
        _timer = NULL;
    }
}

我是iOS的新手，根本不知道该怎么做！非常感谢您提前提供帮助！

ios

objective-c

uibutton

回答 3

Stack Overflow用户

回答已采纳

发布于 2014-06-17 07:52:40

我会用GestureRecognzier来做这件事。以下是一些代码：

- (void)viewDidLoad
{
    [super viewDidLoad];

    UILongPressGestureRecognizer *gr = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(buttonIsPressed:)];
    gr.minimumPressDuration = 0.1;
    [self.button addGestureRecognizer:gr];
}

-(IBAction)buttonIsPressed:(UILongPressGestureRecognizer*)gesture {
    if (gesture.state == UIGestureRecognizerStateBegan) {
        self.label.text = @"Button is pressed!";
    }
    else if (gesture.state == UIGestureRecognizerStateEnded) {
        self.label.text = @"Button is not pressed";
    }
}

标签和按钮需要一个IBOutlet。

票数 1

Stack Overflow用户

发布于 2014-06-17 08:03:01

第一个方法可以做您想做的事情，下面是一个示例实现：

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

    UIButton *myButton = [[UIButton alloc] initWithFrame:CGRectMake(self.view.bounds.size.width / 2.0 - 50.0, self.view.bounds.size.height / 2.0 - 25.0, 100.0, 50.0)];
    myButton.backgroundColor = [UIColor colorWithRed:0.2 green:0.3 blue:0.8 alpha:1.0];
    [myButton setTitle:@"PRESS ME" forState:UIControlStateNormal];
    [myButton addTarget:self action:@selector(setPressed:) forControlEvents:UIControlEventTouchDown];
    [myButton addTarget:self action:@selector(setLetGo:) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:myButton];
}

-(void)setPressed:(id)sender
{
    UIButton *myButton = (UIButton *)sender;

    [myButton setTitle:@"PRESSED" forState:UIControlStateNormal];
}

-(void)setLetGo:(id)sender
{
    UIButton *myButton = (UIButton *)sender;

    [myButton setTitle:@"LET GO" forState:UIControlStateNormal];
}

票数 0