一，效果图。

 

二，工程图。

三，代码。

RootViewController.h

#import 
      
       //加入头文件#import "ComboBoxView.h"@interface RootViewController : UIViewController{    ComboBoxView        *_comboBox;}@end
      

 

RootViewController.m

#import "RootViewController.h"@interface RootViewController ()@end@implementation RootViewController- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        // Custom initialization    }    return self;}- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.        self.navigationController.navigationBarHidden=YES;            NSArray *comboBoxDatasource = [[NSArray alloc] initWithObjects:@"one", @"two", @"three", @"four", @"five", @"six", @"seven", @"eight", nil];    _comboBox = [[ComboBoxView alloc] initWithFrame:CGRectMake(20, 20, 280, 140)];    _comboBox.comboBoxDatasource = comboBoxDatasource;    _comboBox.backgroundColor = [UIColor clearColor];    [_comboBox setContent:[comboBoxDatasource objectAtIndex:0]];    [self.view addSubview:_comboBox];        }