如何做到这一点的效果

Question

我想知道如何做到这一点的效果：

当用户点击初始画面上的加号（见第一个截图），列表会降下来，加号更改为负标志（见秒截图）。

Before http://b223.photo.store.qq.com/psb?/V11ixOec0KfVzE/fJBNAGr5NKNwTnFR7sqIfQWS5qPgVfChmOvMY1g79WY!/b/YZ1h94QZPQAAYpra9YT1PAAA

Answer 1

你必须写你自己的。例如，这里有一个超级简单的例子，告诉你如何隐藏和显示内容。我没有使用图形+/-按钮（而是一个简单的文本按钮），但希望这可以为您提供足够的线索，让您了解如何正确执行此操作。这只是演示了显示文本面板的动画（您可以在此面板上放置图形或其他内容）。

有很多方法可以做到这一点，这太简单了，显然我没有花时间在美学上，但希望它能向你展示一些你可以使用的技巧。我认为关键的技巧就是把东西放到主视图上的UIView上，给它一个零高度，然后动画扩展框架的变化。您也可以移动按钮，更改用于按钮的UIImage等，但您明白了。

// SlideInViewController.m 

#import "SlideInViewController.h" 

@interface SlideInViewController() 
{ 
    UIView *_hiddenPanel; 
    UIButton *_hideShowButton; 
    BOOL _panelHidden; 
} 
@end 

@implementation SlideInViewController 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    // initialize the flag 

    _panelHidden = YES; 

    // create the panel that will be hidden initially (height of zero), but will be revealed when you click on the button 

    _hiddenPanel = [[UIView alloc] initWithFrame:CGRectMake(0.0, 300.0, self.view.frame.size.width, 0.0)]; 
    _hiddenPanel.clipsToBounds = YES; 
    [self.view addSubview:_hiddenPanel]; 

    // add the button 

    _hideShowButton = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
    _hideShowButton.frame = CGRectMake(40.0, 260.0, 40.0, 40.0); 
    [_hideShowButton setTitle:@"+" forState:UIControlStateNormal]; 
    [_hideShowButton addTarget:self action:@selector(hideShowPanel:) forControlEvents:UIControlEventTouchUpInside]; 
    [self.view addSubview:_hideShowButton]; 

    // now put whatever you want on this hidden panel. 

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0.0, 0.0, self.view.frame.size.width, 200.0)]; 
    label.lineBreakMode = UILineBreakModeWordWrap; 
    label.numberOfLines = 0; 
    label.text = @"This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. This is a very long label. "; 
    [_hiddenPanel addSubview:label]; 

    // Do any additional setup after loading the view. 
} 

- (IBAction)hideShowPanel:(id)sender 
{ 
    if (_panelHidden) 
    { 
     // if the panel was already hidden, let's reveal it (and move/adjust the button accordingly) 

     [UIView animateWithDuration:1.0 animations:^{ 
      _hideShowButton.frame = CGRectMake(40.0, 60.0, 40.0, 40.0); 
      [_hideShowButton setTitle:@"-" forState:UIControlStateNormal]; 

      _hiddenPanel.frame = CGRectMake(0.0, 100.0, self.view.frame.size.width, 200.0); 
     }]; 
    } 
    else 
    { 
     // if the panel was already shown, so now let's hide it again (and move/adjust the button accordingly) 
     [UIView animateWithDuration:1.0 animations:^{ 
      _hideShowButton.frame = CGRectMake(40.0, 260.0, 40.0, 40.0); 
      [_hideShowButton setTitle:@"+" forState:UIControlStateNormal]; 

      _hiddenPanel.frame = CGRectMake(0.0, 300.0, self.view.frame.size.width, 0.0); 
     }]; 
    } 

    _panelHidden = !_panelHidden; 
} 

@end