element-ios/Vector/Categories/UIViewController+VectorSearch.m

/*
 Copyright 2015 OpenMarket Ltd

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import "UIViewController+VectorSearch.h"

#import <objc/runtime.h>

/**
 `UIViewController_VectorSearch` is the internal single point storage for the search feature.
 
 It hosts all required data so that only one associated object can be used in the category.
 */
@interface UIViewController_VectorSearch : NSObject

// The search bar
@property (nonatomic) UISearchBar *searchBar;
@property (nonatomic) BOOL searchBarHidden;

// Backup of view when displaying search
@property (nonatomic) UIView *backupTitleView;
@property (nonatomic) UIBarButtonItem *backupLeftBarButtonItem;
@property (nonatomic) UIBarButtonItem *backupRightBarButtonItem;

// The Vector empty search background image (champagne bubbles)
@property (nonatomic) UIImageView *backgroundImageView;
@property (nonatomic) NSLayoutConstraint *backgroundImageViewBottomConstraint;

@end

@implementation UIViewController_VectorSearch
@end


#pragma mark - UIViewController+VectorSearch
#pragma mark -

@interface UIViewController ()

// The single associated object hosting all data.
@property(nonatomic) UIViewController_VectorSearch *searchInternals;

@end

@implementation UIViewController (VectorSearch)

- (UISearchBar *)searchBar
{
    return self.searchInternals.searchBar;
}

- (BOOL)searchBarHidden
{
    return self.searchInternals.searchBarHidden;
}

- (UIImageView*)backgroundImageView
{
    return self.searchInternals.backgroundImageView;
}

- (void)showSearch:(BOOL)animated
{
    // Backup screen header before displaying the search bar in it
    self.searchInternals.backupTitleView = self.navigationItem.titleView;
    self.searchInternals.backupLeftBarButtonItem = self.navigationItem.leftBarButtonItem;
    self.searchInternals.backupRightBarButtonItem = self.navigationItem.rightBarButtonItem;
    self.searchInternals.searchBarHidden = NO;

    // Reset searches
    self.searchBar.text = @"";

    // Remove navigation buttons
    self.navigationItem.hidesBackButton = YES;
    self.navigationItem.rightBarButtonItem = nil;
    self.navigationItem.leftBarButtonItem = nil;

    // Add the search bar and
    self.navigationItem.titleView = self.searchBar;
    [self.searchBar becomeFirstResponder];
}

- (void)hideSearch:(BOOL)animated
{
    // Restore the screen header
    if (self.searchInternals.backupLeftBarButtonItem)
    {
        self.navigationItem.hidesBackButton = NO;
        self.navigationItem.titleView = self.searchInternals.backupTitleView;
        self.navigationItem.leftBarButtonItem = self.searchInternals.backupLeftBarButtonItem;
        self.navigationItem.rightBarButtonItem = self.searchInternals.backupRightBarButtonItem;
    }

    self.searchInternals.searchBarHidden = YES;
}

- (void)addBackgroundImageViewToView:(UIView*)view
{
    UIImageView *backgroundImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"search_bg"]];
    backgroundImageView.translatesAutoresizingMaskIntoConstraints = NO;

    [view addSubview:backgroundImageView];

    // Keep it at left
    NSLayoutConstraint *leftConstraint = [NSLayoutConstraint constraintWithItem:view
                                                                      attribute:NSLayoutAttributeLeading
                                                                      relatedBy:NSLayoutRelationEqual
                                                                         toItem:backgroundImageView
                                                                      attribute:NSLayoutAttributeLeading
                                                                     multiplier:1.0
                                                                     constant:0];
    // Same width as parent
    NSLayoutConstraint *widthConstraint = [NSLayoutConstraint constraintWithItem:view
                                                                       attribute:NSLayoutAttributeWidth
                                                                       relatedBy:NSLayoutRelationEqual
                                                                          toItem:backgroundImageView
                                                                       attribute:NSLayoutAttributeWidth
                                                                      multiplier:1.0f
                                                                        constant:0.0f];

    // Keep the image aspect ratio
    NSLayoutConstraint *aspectRatioConstraint = [NSLayoutConstraint
                                                  constraintWithItem:backgroundImageView
                                                  attribute:NSLayoutAttributeHeight
                                                  relatedBy:NSLayoutRelationEqual
                                                  toItem:backgroundImageView
                                                  attribute:NSLayoutAttributeWidth
                                                  multiplier:(backgroundImageView.frame.size.height / backgroundImageView.frame.size.width)
                                                  constant:0];

    // Set its position according to its bottom
    NSLayoutConstraint *bottomConstraint = [NSLayoutConstraint constraintWithItem:view
                                                                        attribute:NSLayoutAttributeBottom
                                                                        relatedBy:NSLayoutRelationEqual
                                                                           toItem:backgroundImageView
                                                                        attribute:NSLayoutAttributeBottom
                                                                       multiplier:1.0f
                                                                         constant:216];

    [NSLayoutConstraint activateConstraints:@[leftConstraint,
                                              widthConstraint,
                                              aspectRatioConstraint,
                                              bottomConstraint
                                              ]];

    self.searchInternals.backgroundImageView = backgroundImageView;
    self.searchInternals.backgroundImageViewBottomConstraint = bottomConstraint;
}

- (void)setKeyboardHeightForBackgroundImage:(CGFloat)keyboardHeight
{
    // keyboardHeight = 0 means no keyboard, so filter it out
    if (keyboardHeight > 0)
    {
        // 60 = 18 + 42 from the Vector design
        self.searchInternals.backgroundImageViewBottomConstraint.constant = keyboardHeight - 60;
    }
}

#pragma mark - UISearchBarDelegate

- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar2
{
    // "Search" key has been pressed
    [self.searchBar resignFirstResponder];
}

- (void)searchBarCancelButtonClicked:(UISearchBar *)searchBar2
{
    [self hideSearch:YES];
}

- (BOOL)searchBarShouldEndEditing:(UISearchBar *)searchBar2
{
    // Keep the search bar cancel button enabled even if the keyboard is not displayed
    dispatch_async(dispatch_get_main_queue(), ^{
        for (UIView *subView in self.searchBar.subviews)
        {
            for (UIView *view in subView.subviews)
            {
                if ([view isKindOfClass:[UIButton class]])
                {
                    [(UIButton *)view setEnabled:YES];
                }
            }
        }
    });
    return YES;
}

#pragma mark - Internal associated object

- (void)setSearchInternals:(UIViewController_VectorSearch *)searchInternals
{
    objc_setAssociatedObject(self, @selector(searchInternals), searchInternals, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (UIViewController_VectorSearch *)searchInternals
{
    UIViewController_VectorSearch *searchInternals = objc_getAssociatedObject(self, @selector(searchInternals));
    if (!searchInternals)
    {
        // Initialise internal data at the first call
        searchInternals = [[UIViewController_VectorSearch alloc] init];

        UISearchBar *searchBar = [[UISearchBar alloc] init];
        searchBar.showsCancelButton = YES;
        searchBar.delegate = (id<UISearchBarDelegate>)self;
        searchInternals.searchBar = searchBar;

        self.searchInternals = searchInternals;
    }
    return searchInternals;
}

@end