InfoBarStackView/Common/DisclosureViewController.m

/*
     File: DisclosureViewController.m
 Abstract: The main view controller (base view controller) for each view in the NSStackView.
  Version: 1.0
 
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 */
 
#import "DisclosureViewController.h"
@import QuartzCore;   // for kCAMediaTimingFunctionEaseInEaseOut
 
@interface DisclosureViewController ()
{
    NSView *_disclosedView;
}
@property (weak) IBOutlet NSTextField *titleTextField;      // the title of the discloved view
@property (weak) IBOutlet NSButton *disclosureButton;       // the hide/show button
@property (weak) IBOutlet NSView *headerView;               // header/title section of this view controller
 
@property (strong) NSLayoutConstraint *closingConstraint;   // layout constraint applied to this view controller when closed
 
@end
 
 
#pragma mark -
 
@implementation DisclosureViewController
{
    BOOL _disclosureIsClosed;
}
 
- (id)init
{
    return [self initWithNibName:@"DisclosureViewController" bundle:nil];
}
 
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self != nil)
    {
        _disclosureIsClosed = NO;
    }
    return self;
}
 
- (void)awakeFromNib
{
    _disclosureIsClosed = NO;
}
 
- (void)setTitle:(NSString *)title
{
    [super setTitle:title];
    [self.titleTextField setStringValue:title];
}
 
- (NSView *)disclosedView
{
    return _disclosedView;
}
 
- (void)setDisclosedView:(NSView *)disclosedView
{
    if (_disclosedView != disclosedView)
    {
        [self.disclosedView removeFromSuperview];
        _disclosedView = disclosedView;
        [self.view addSubview:self.disclosedView];
        
        // we want a white background to distinguish between the
        // header portion of this view controller containing the hide/show button
        //
        self.disclosedView.wantsLayer = YES;
        self.disclosedView.layer.backgroundColor = [[NSColor whiteColor] CGColor];
        
        [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_disclosedView]|"
                                                                          options:0
                                                                          metrics:nil
                                                                            views:NSDictionaryOfVariableBindings(_disclosedView)]];
        [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[_headerView][_disclosedView]"
                                                                          options:0
                                                                          metrics:nil
                                                                            views:NSDictionaryOfVariableBindings(_headerView, _disclosedView)]];
        
        // add an optional constraint (but with a priority stronger than a drag), that the disclosing view
        [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[_disclosedView]-(0@600)-|"
                                                                          options:0 metrics:nil
                                                                            views:NSDictionaryOfVariableBindings(_disclosedView)]];
    }
}
 
// The hide/show button was clicked
//
- (IBAction)toggleDisclosure:(id)sender
{
    if (!_disclosureIsClosed)
    {
        CGFloat distanceFromHeaderToBottom = NSMinY(self.view.bounds) - NSMinY(self.headerView.frame);
 
        if (!self.closingConstraint)
        {
            // The closing constraint is going to tie the bottom of the header view to the bottom of the overall disclosure view.
            // Initially, it will be offset by the current distance, but we'll be animating it to 0.
            self.closingConstraint = [NSLayoutConstraint constraintWithItem:self.headerView attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeBottom multiplier:1 constant:distanceFromHeaderToBottom];
        }
        self.closingConstraint.constant = distanceFromHeaderToBottom;
        [self.view addConstraint:self.closingConstraint];
    
        [NSAnimationContext runAnimationGroup:^(NSAnimationContext *context) {
            context.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
            // Animate the closing constraint to 0, causing the bottom of the header to be flush with the bottom of the overall disclosure view.
            self.closingConstraint.animator.constant = 0;
            self.disclosureButton.title = @"Show";
        } completionHandler:^{
            _disclosureIsClosed = YES;
        }];
    }
    else
    {
        [NSAnimationContext runAnimationGroup:^(NSAnimationContext *context) {
            context.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
            // Animate the constraint to fit the disclosed view again
            self.closingConstraint.animator.constant -= self.disclosedView.frame.size.height;
            self.disclosureButton.title = @"Hide";
        } completionHandler:^{
            // The constraint is no longer needed, we can remove it.
            [self.view removeConstraint:self.closingConstraint];
            _disclosureIsClosed = NO;
        }];
    }
}
 
@end