ios学习--iphone 实现下拉菜单

http://blog.163.com/ytrtfhj@126/blog/static/8905310920116224445195/
 
通过网上资料，自己借助资料写的代码，这是完全代码

//****************************************************************************

@interface DropDown1 :
UIView <UITableViewDelegate,UITableViewDataSource> {
   
UITableView *tv;//下拉列表
    NSArray *tableArray;//下拉列表数据
    UITextField *textField;//文本输入框
    BOOL showList;//是否弹出下拉列表
    CGFloat tabheight;//table下拉列表的高度
    CGFloat frameHeight;//frame的高度
}

@property (nonatomic,retain)
UITableView *tv;
@property (nonatomic,retain)
NSArray *tableArray;
@property (nonatomic,retain)
UITextField *textField;

@end

//****************************************************************************

@implementation DropDown1

@synthesize tv,tableArray,textField;

- (void)dealloc
{
    [tv
release];
    [tableArray
release];
    [textField
release];
    [super
dealloc];
}

-(id)initWithFrame:(CGRect)frame
{
    if (frame.size.height<200) {
        frameHeight =
200;
    }else{
        frameHeight = frame.size.height;
    }
   
tabheight = frameHeight-30;
    
    frame.size.height =
30.0f;
    
    self=[super
initWithFrame:frame];

    if(self){
        showList =
NO; //默认不显示下拉框
        
        tv = [[UITableView
alloc] initWithFrame:CGRectMake(0,
30, frame.size.width,
0)]; 
        tv.delegate =
self;
        tv.dataSource =
self;  
       
tv.backgroundColor = [UIColor
grayColor];  
       
tv.separatorColor = [UIColor
lightGrayColor];  
        tv.hidden =
YES;  
        [self
addSubview:tv];  

        textField = [[UITextField
alloc] initWithFrame:CGRectMake(0,
0, frame.size.width,
30)];
       
textField.borderStyle=UITextBorderStyleRoundedRect;//设置文本框的边框风格
        [textField
addTarget:self
action:@selector(dropdown)
forControlEvents:UIControlEventAllTouchEvents];
        [self
addSubview:textField];
        
    }
   
return self;
}
-(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
        
        CGRect sf =
self.frame;
        sf.size.height =
frameHeight;
        
       
//把dropdownList放到前面，防止下拉框被别的控件遮住
        [self.superview
bringSubviewToFront:self];
        tv.hidden =
NO;
        showList =
YES;//显示下拉框
        
        CGRect frame =
tv.frame;
        frame.size.height =
0;
        tv.frame = frame;
        frame.size.height =
tabheight;
        [UIView
beginAnimations:@"ResizeForKeyBoard"
context:nil]; 
        [UIView
setAnimationCurve:UIViewAnimationCurveLinear];  
        self.frame = sf;
        tv.frame = frame;
        [UIView
commitAnimations];
    }
}

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
   
return [tableArray
count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static
NSString *CellIdentifier =
@"Cell";
    
    UITableViewCell *cell = [tableView
dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell ==
nil) {
        cell = [[[UITableViewCell
alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier] autorelease];
    }
    
    cell.textLabel.text = [tableArray
objectAtIndex:[indexPath
row]];
    cell.textLabel.font = [UIFont
systemFontOfSize:16.0f];
    cell.accessoryType =
UITableViewCellAccessoryNone;
    cell.selectionStyle =
UITableViewCellSelectionStyleGray;
    
    return cell;
}
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return
35;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    textField.text = [tableArray
objectAtIndex:[indexPath
row]];
    showList =
NO;
    tv.hidden =
YES;
    
    CGRect sf = self.frame;

    sf.size.height = 30;

    self.frame = sf;
    CGRect frame = tv.frame;

    frame.size.height = 0;

    tv.frame = frame;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
   
// Return YES for supported orientations
    return (interfaceOrientation ==
UIInterfaceOrientationPortrait);
}

@end

//****************************************************************************

上面的是实现方法，下面是使用：

 DropDown1 *dd1 = [[DropDown1
alloc] initWithFrame:CGRectMake(10,
10,
140, 100)];
 dd1.textField.placeholder =
@"请输入联系方式";
 NSArray* arr=[[NSArray
alloc]initWithObjects:@"电话",@"email",@"手机",@"aaa",@"bbb",@"ccc",nil];
 dd1.tableArray = arr;
 [arr release];
 [self.view
addSubview:dd1];
 [dd1 release];