iphone界面如何实现下拉列表2

  //下拉列表

    listView=[[UITableView alloc]initWithFrame:

      CGRectMake(lineWidth,oldFrame.size.height+lineWidth, 

    oldFrame.size.width-lineWidth*2,

    oldFrame.size.height*4-lineWidth*2)];

    listView.dataSource=self;

    listView.delegate=self;

    listView.backgroundColor=listBgColor;

    listView.separatorColor=lineColor;

    listView.hidden=!showList;//一开始listView是隐藏的，此后根据showList的值显示或隐藏

     

    [self addSubview:listView]; 

    [listView release];

    }

    -(void)dropdown{

    [textField resignFirstResponder];

    if(showList)
{//如果下拉框已显示，什么都不做

    return;

    }else{//如果下拉框尚未显示，则进行显示

    //把dropdownList放到前面，防止下拉框被别的控件遮住

     

    [self.superview
bringSubviewToFront:self];

    [self setShowList:YES];//显示下拉框

    }

    }

    #pragma mark listViewdataSource method and delegate method

    -(NSInteger)tableView:(UITableView *)table numberOfRowsInSection:(NSInteger)section{

    return list.count;

    }

    -(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

    static NSString
*cellid=@"listviewid";

    UITableViewCell* cell=[tableView dequeueReusableCellWithIdentifier:cellid];

    if(cell==nil){

    cell=[[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault

      reuseIdentifier:cellid]autorelease];

    }

    //文本标签

    cell.textLabel.text=(NSString*)[list objectAtIndex:indexPath.row];

    cell.textLabel.font=textField.font;

    cell.selectionStyle=UITableViewCellSelectionStyleGray;

    return cell;

    }

    -(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{

    return oldFrame.size.height;

    }

    //当选择下拉列表中的一行时，设置文本框中的值，隐藏下拉列表

    -(void)tableView:(UITableView
*)tableViewdidSelectRowAtIndexPath:(NSIndexPath *)indexPath{

    //NSLog(@"select");

    textField.text=(NSString*)[list objectAtIndex:indexPath.row];

    //NSLog(@"textField.text=%@",textField.text);

    [self setShowList:NO];

    }

    -(BOOL)showList{//setShowList:No为隐藏，setShowList:Yes为显示

    return showList;

    }

    -(void)setShowList:(BOOL)b{

    showList=b;

    NSLog(@"showlist
is set ");

    if(showList){

    self.frame=newFrame;

    }else {

    self.frame=oldFrame;

    }

    listView.hidden=!b;

    }

    /*

    - (void)drawRect:(CGRect)rect {

        // Drawing code.

    }

    */

    - (void)dealloc
{

        [super dealloc];

    }

    @end