关于NavigationItem.rightBarButtonItem设置

第一种：

UIImage *searchimage=[UIImage imageNamed:@"search.png"];

    UIBarButtonItem *barbtn=[[UIBarButtonItem alloc] initWithImage:nil style:UIBarButtonItemStyleDone target:self action:@selector(searchprogram)];    

    barbtn.image=searchimage;

    self.navigationItem.rightBarButtonItem=barbtn;

这种设置出来的外观不好控制

第二种：

UIButton*rightButton = [[UIButtonalloc]initWithFrame:CGRectMake(0,0,30,30)];

    [rightButtonsetImage:[UIImageimageNamed:@"search.png"]forState:UIControlStateNormal];

    [rightButtonaddTarget:selfaction:@selector(searchprogram)forControlEvents:UIControlEventTouchUpInside];

   UIBarButtonItem*rightItem = [[UIBarButtonItemalloc]initWithCustomView:rightButton];

    [rightButton release];

   self.navigationItem.rightBarButtonItem= rightItem;

    [rightItem release];

这种图片将填满button，大小可控

第三种：

UIBarButtonItem *anotherButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemBookmarks target:self action:@selector(methodtocall:) ]; 

如何让navigationItem.rightBarButtonItem隐藏消失？

self.navigationItem.rightBarButtonItem=nil；

即可实现