[IOS] Drop-down bar implementation

1. Ideas:

1. Use UITableViewController to display data

2. Pass data through delegate

3. Load UITableViewController on the page and add UITableViewController.view

 

2. Realize:

1. UITableViewController:

DropDownMenuTableViewController.h：

 

#import <UIKit/UIKit.h>

@protocol DropDownMenuDelegate <NSObject>
/**
 * Selected cell's proxy event
 */
- (void) selectedCell:(NSInteger)index;

/**
 * Update the height of the dropdown menu
 */
//- (void) updateListH;

@end


@interface DropDownMenuTableViewController : UITableViewController

@property (nonatomic) BOOL isOpen;

@property (nonatomic) NSArray *dataSource;

@property (nonatomic,weak) id<DropDownMenuDelegate>dropDownMenuDelegate;

@end

 

 

DropDownMenuTableViewController.m:

 

#import "DropDownMenuTableViewController.h"

@interface DropDownMenuTableViewController ()

@end

@implementation DropDownMenuTableViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // background transparent
    self.view.backgroundColor = [UIColor whiteColor];
    // remove redundant dividing lines
    [self.tableView setTableFooterView:[[UIView alloc]initWithFrame:CGRectZero]];
    [self.tableView setSeparatorStyle:UITableViewCellSeparatorStyleNone];
    // close the dropdown list by default
    _isOpen = NO;
    
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    
    // Expand and hide the account list
    if(_isOpen)
        return _dataSource.count;
    else
        return 0;
    
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    NSString *specialId = @"id";
    UITableViewCell *cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:specialId];
    // add data source
    cell.textLabel.text = [_dataSource objectAtIndex:indexPath.row];
    cell.textLabel.textAlignment = NSTextAlignmentCenter;
    return cell;
}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    //Notify agent
    [_dropDownMenuDelegate selectedCell:indexPath.row];
    
    
}


@end

 

 

2.ViewController:

@interface MainViewController ()<GridTableDelegate>

 

@property (strong, nonatomic) IBOutlet UITextField *encryption_text;

 

@property (nonatomic) NSArray *encryption_dataSource;
@property (nonatomic) DropDownMenuTableViewController *encrypt_dropDownMenuTable;

 Prepare the data source yourself

 

 

Manually initialize the drop-down view:

 

-(void)initView{
    
    //set text field not editable
    _encryption_text.enabled = false;
    
    _encrypt_dropDownMenuTable = [[DropDownMenuTableViewController alloc]init];
    // Set the proxy of the popup menu to the current class
    _encrypt_dropDownMenuTable.dropDownMenuDelegate = self;
    
    // The data is passed to the drop-down list class as the data source of the table
    _encrypt_dropDownMenuTable.dataSource = _encryption_dataSource;
    
    // Add the dropdown list as a subpage to the current view, and add a subcontroller at the same time
    [self addChildViewController:_encrypt_dropDownMenuTable];
    
    // Set the position and size of the popup menu according to the size of the display box
    CGFloat encryptTv_x      = _encryption_text.frame.origin.x;
    CGFloat encryptTv_y      = _encryption_text.frame.origin.y;
    CGFloat encryptTv_width  = _encryption_text.frame.size.width;
    CGFloat encryptTv_height = _encryption_text.frame.size.height;
    
    _encrypt_dropDownMenuTable.view.frame = CGRectMake(encryptTv_x, encryptTv_y + encryptTv_height, encryptTv_width, 0.15*screen_height);
    
}

 

After clicking the button, a drop-down box will pop up:

- (IBAction)encryptDropDownMenuBtnClicked:(UIButton *)sender {
    NSLog(@"encrypt drop down menu isOpen:%d",_encrypt_dropDownMenuTable.isOpen);
    if (_encrypt_dropDownMenuTable.isOpen) {
        [_encrypt_dropDownMenuTable.view removeFromSuperview];
    }else{
        [_pop_view addSubview:_encrypt_dropDownMenuTable.view];
        [_channel_dropDownMenuTable.view removeFromSuperview];
    }
    _encrypt_dropDownMenuTable.isOpen = !_encrypt_dropDownMenuTable.isOpen;
    [_encrypt_dropDownMenuTable.tableView reloadData];
    // handle scrollbars
    [_encrypt_dropDownMenuTable.tableView performSelector:@selector(flashScrollIndicators) withObject:nil afterDelay:0];
}

 *Be careful to remove the view of the tableview, because even if the counts becomes 0, it will block the following controls;

 

Set the table click event:

/**
 * The selected cell gets the proxy monitoring of the selected account
 */
- (void)selectedCell:(NSInteger)index {
    // Update the currently selected account
    _encryption_text.text = [_encryption_dataSource objectAtIndex:index];
    
    //close table view
    _encrypt_dropDownMenuTable.isOpen = NO;
    [_encrypt_dropDownMenuTable.tableView reloadData];
    [_encrypt_dropDownMenuTable.view removeFromSuperview];
    
}

 

 

refer to:

1.http://blog.csdn.net/cordova/article/details/51607142