IOS代码笔记之下拉菜单效果

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController

@end 

#import "RootViewController.h"
#import "NIDropDown.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.title=@"DropDown";
 
 UIButton *button=[UIButton buttonWithType:UIButtonTypeRoundedRect];
 button.frame=CGRectMake(10, 100, 150,30);
 button.backgroundColor=[UIColor redColor];
 [button addTarget:self action:@selector(doClickAction:) forControlEvents:UIControlEventTouchUpInside];
 [self.view addSubview:button];
 
 
 
 
}
-(void)doClickAction:(UIButton *)btn
{
 NSArray *dataArray=[NSArray arrayWithObjects:@"1",@"2",@"3",@"4",@"5", nil];
 
 NIDropDown *dropDown=[[NIDropDown alloc]init];
 [dropDown showDropDown:btn andHeight:[dataArray count]*36 andData:dataArray];
 [self.view addSubview:dropDown];
}