一，效果图。
二，工程图。
三，代码。
RootViewController.h
#import <UIKit/UIKit.h>
//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];}
