navigationItem的leftBarButtonItem和rightBarButtonItem隐藏

- (void)showEdit {

if (不符合显示条件) {

self.navigationItem.rightBarButtonItem.customView.hidden = YES;
　　　//[self.navigationItem.rightBarButtonItem.customView setAlpha:0.0];

} else{

self.navigationItem.rightBarButtonItem.customView.hidden = NO;
　　　//[self.navigationItem.rightBarButtonItem.customView setAlpha:1.0];

}

}

经过亲自尝试,该种方法并不能实现隐藏和显示功能,于是,尝试用下面这种方法成功解决了问题

- (void)showEdit {

if (符合显示条件) {

if (self.navigationItem.rightBarButtonItem == nil) {

self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"编辑" style:UIBarButtonItemStyleDone target:self action:@selector(edit:)];

}

} else{

if (self.navigationItem.rightBarButtonItem) {

self.navigationItem.rightBarButtonItem = nil;

}

}

}