iOS开发导航栏控件的作用

一，在iOS开发过程中针对一些导航栏上需要自定义视图的情况，有时候需要用系统自带的处理，有些时候需要自定义一些视图并把视图添加上去，这时候主要是它们的位置有些许差别，下面简单写下demo；

1，用导航栏系统自带的视图处理：

 1     //1 中间的图片
 2     UIImageView *imageBarView = [[UIImageView alloc] initWithFrame:CGRectMake(kScreenWidth / 2.f - 40.f, 20.f, 80, 30)];
 3     imageBarView.image = [UIImage imageNamed:@"中间视图名称"];
 4     self.navigationItem.titleView = imageBarView;
 5     
 6     
 7     //2 导航栏右边的分类按钮
 8     UIButton *buttonRightItem = [UIButton buttonWithType:UIButtonTypeCustom];
 9     buttonRightItem.frame = CGRectMake(0.f, 0.f, 50.f, 30.f);
10     [buttonRightItem setTitle:@"分类" forState:UIControlStateNormal];
11     [buttonRightItem setTitleColor:[UIColor colorWithRed:0.310 green:0.598 blue:0.156 alpha:1.000] forState:UIControlStateNormal];
12     buttonRightItem.titleLabel.font = [UIFont systemFontOfSize:17];
13     [buttonRightItem addTarget:self action:@selector(buttonRightAction:) forControlEvents:UIControlEventTouchUpInside];
14     self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:buttonRightItem];
15     
16     //3 导航栏左侧的APP按钮
17     UIButton *buttonLeftItem = [UIButton buttonWithType:UIButtonTypeCustom];
18     buttonLeftItem.frame = CGRectMake(0.f, 0.f, 64.f, 64.f);
19     [buttonLeftItem setImage:[UIImage imageNamed:@"左侧视图"] forState:UIControlStateNormal];
20     buttonLeftItem.imageEdgeInsets = UIEdgeInsetsMake(0.f, -30.f, 0.f, 0.f);//用来调节相对位置
21     [buttonLeftItem addTarget:self action:@selector(buttonLeftAction:) forControlEvents:UIControlEventTouchUpInside];
22     self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:buttonLeftItem];

其实以上关键是：

self.navigationItem.titleView = imageBarView;self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:buttonRightItem];

self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:buttonLeftItem];

主要是上面的三句话，这个优点是左，中，右三个按钮的响应事件的区域比较大，比较容易调控，一般建议用系统自带的来操作；

缺点也有，就是每个区域只能放一个控件，下面用自定义的方法来在同一个区域放两个或以上的控件；

2，自定义导航栏上的视图；

 1      rightButton = [UIButton buttonWithType:UIButtonTypeCustom];
 2     rightButton.backgroundColor = [UIColor blackColor];
 3     [rightButton setTitle:@"分享" forState:UIControlStateNormal];
 4     [rightButton addTarget:self action:@selector(shareAction:) forControlEvents:UIControlEventTouchUpInside];
 5     rightButton.frame = CGRectMake(self.view.width - 50.f,0.f, 50.f, 44.f);
 6     [self.navigationController.navigationBar addSubview:rightButton];
 7     
 8     rightTwoButton = [UIButton buttonWithType:UIButtonTypeCustom];
 9     rightTwoButton.backgroundColor = [UIColor blueColor];
10     [rightTwoButton setTitle:@"收藏" forState:UIControlStateNormal];
11     [rightTwoButton addTarget:self action:@selector(storeAction:) forControlEvents:UIControlEventTouchUpInside];
12     rightTwoButton.frame = CGRectMake(self.view.width - 100.f, 0.f, 50.f, 44.f);
13     [self.navigationController.navigationBar addSubview:rightTwoButton];

以上方法可以把视图很任性的放在导航栏的任何位置，因为用的是 self.navigationController.navigationBar 来添加的，这个是代表整个导航栏，但是这个的frame需要认真调节，不然的话布局会很难看，除此之外，当当起视图要出现或者消失时还需要对这个按钮进行处理；

 1 - (void)viewWillDisappear:(BOOL)animated
 2 {
 3     [super viewWillDisappear:animated];
 4     
 5     [UIView animateWithDuration:0.2 animations:^{
 6         
 7         rightButton.alpha = 0;
 8         rightTwoButton.alpha = 0;
 9 
10     }];
11 }
12 
13 - (void)viewWillAppear:(BOOL)animated{
14     
15     [super viewWillAppear:animated];
16     [UIView animateWithDuration:0.2 animations:^{
17         
18         rightButton.alpha = 1;
19         rightTwoButton.alpha = 1;
20         
21     }];
22 
23 }

以上就是导航栏上视图的处理，可能比较简单，但是对初学者来说也是比较重要的；

小技巧：消除导航栏下方的阴影办法：

// 添加上这一句，可以去掉导航条下边的shadowImage，就可以正常显示了

self.navigationController.navigationBar.shadowImage = [[UIImage alloc] init];

self.navigationController.navigationBar.translucent = NO;

来源：https://www.cnblogs.com/RiversMa/p/4725735.html

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