UINavigationController特性总结(2)

1.navigationItem设置

navigationItem可以设置:

属性 效果
title 标题
titleView 标题视图(UIView)
leftBarButtonItem 左边的按钮(UIBarButtonItem)
leftBarButtonItems 左边的按钮们(UIBarButtonItem数组)
rightBarButtonItem 右边的按钮
rightBarButtonItems 右边的按钮们
backBarButonItem 返回按钮(UIBarButtonItem)
prompt 描述

1.1 title/leftBarButtonItem/rightBarButtonItems设置

#import "ViewController.h"
@interface ViewController ()
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.view setBackgroundColor:[UIColor orangeColor]];
    
    self.navigationController.navigationBar.translucent = NO;

    CGFloat w = [UIScreen mainScreen].bounds.size.width;
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(8, 0, w-16, 220)];
    imageView.image = [UIImage imageNamed:@"hy.jpg"];
    [self.view addSubview:imageView];
    
    UIBarButtonItem *item1 = [[UIBarButtonItem alloc] initWithTitle:@"item1" style:UIBarButtonItemStylePlain target:self action:@selector(btnClicked:)];
    UIBarButtonItem *item2 = [[UIBarButtonItem alloc] initWithTitle:@"item2" style:UIBarButtonItemStylePlain target:self action:@selector(btnClicked:)];
    self.navigationItem.title = @"Hello World";
    self.navigationItem.leftBarButtonItem = item1;
    self.navigationItem.rightBarButtonItems = @[item1,item2];
    
    //leftItems/rightItems的颜色
    self.navigationController.navigationBar.tintColor = [UIColor redColor];
    //设置NavigationBar背景颜色
    self.navigationController.navigationBar.barTintColor = [UIColor greenColor];
    //设置title的文字颜色
    self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName:[UIColor yellowColor]};

需要注意的是 navigationController和 navigationBar和 navigationItem三者的关系,这一点在下一小节论述.
还有,要记得如何设置title的颜色,如何设置items的颜色,如何设置navigationBar的颜色.

效果:
UINavigationController特性总结(2)_第1张图片
效果.png

1.2 prompt设置

#import "ViewController.h"
@interface ViewController ()
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.view setBackgroundColor:[UIColor orangeColor]];
    
    self.navigationController.navigationBar.translucent = NO;

    CGFloat w = [UIScreen mainScreen].bounds.size.width;
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(8, 0, w-16, 220)];
    imageView.image = [UIImage imageNamed:@"hy.jpg"];
    [self.view addSubview:imageView];

    self.navigationItem.title = @"Hello World";
 
    //描述信息,navigationBar高度增加30,由44变成74
    self.navigationItem.prompt = @"this is prompt";
    
}

prompt属性用来添加描述信息,赋值后,navigationBar高度增加30,由44变成74

效果
UINavigationController特性总结(2)_第2张图片
效果

1.3 titleView设置

#import "ViewController.h"
@interface ViewController ()
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.view setBackgroundColor:[UIColor orangeColor]];
    
    self.navigationController.navigationBar.translucent = NO;
 
    CGFloat w = [UIScreen mainScreen].bounds.size.width;
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(8, 0, w-16, 220)];
    imageView.image = [UIImage imageNamed:@"hy.jpg"];
    [self.view addSubview:imageView];

    UIView *titleView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 30)];
    UILabel *titleLabe = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 100, 30)];
    titleLabe.text = @"newtitle";
    titleLabe.textAlignment = NSTextAlignmentCenter;
    titleLabe.textColor = [UIColor redColor];
    [titleView addSubview:titleLabe];
    titleView.backgroundColor = [UIColor yellowColor];
    self.navigationItem.titleView = titleView;
}
注意

如果需要在 self.navigationItem.titleView 中添加子控件,需要先实例化一次self.navigationItem.titleView:
self.navigationItem.titleView = [[UIView alloc] init];
不然无论你忘titleView中放多少控件,都是显示不出来的.

效果
UINavigationController特性总结(2)_第3张图片
效果

1.4 自定义返回按钮

-(void)btnClicked:(UIBarButtonItem *)sender{
    UIViewController *vc = [[UIViewController alloc] init];
    vc.view.backgroundColor = [UIColor purpleColor];
    UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithTitle:@"自定义返回" style:UIBarButtonItemStylePlain target:vc action:nil];
    vc.navigationItem.leftBarButtonItem = backItem;
    [self.navigationController pushViewController:vc animated:YES];
}

自定义返回按钮,最简单的方法就是,设置push出了的新控制器的leftBarButtonItem,当leftBarButtonItem设置好之后, backBarButonItem就不显示了.


UINavigationController特性总结(2)_第4张图片
效果

2. navigationBar和 navigationItem的关系

(该小节参考:http://blog.csdn.net/luoyeffcs/article/details/16106707/)
先看一下这些类的继承关系,可以看清很多问题.

继承自
UINavigationController UIViewController
UINavigationBar UIView
UINavigationItem NSObject
UIBarButtonItem UIBarItem
UIBarItem NSObject
问题1

navigationItem和navigationController都是UIViewController的属性,而UINavigationController的父类就是UIViewController,所以会出现:
self.navigationController.navigationController
self.navigationController.navigationItem这种现象(self指UIViewController).而这应该是被忽略的属性(没啥乱用,容易混淆).

navigationItem是UIViewController的属性,
正确设置navigationItem:self. navigationItem
navigationBar是UINavigationController的属性,
正确设置navigationBar :self.navigationController.navigationBar

问题2

self.title 和self.navigationItem.title 和self.tabBarItem.title
由于UIViewController本身包含navigationItem和tabBarItem,所以可以单独对其title赋值,self.title会重写另外两个的值,只是提供的一种便利方法。

当self.title = @"123"时, self.navigationItem.title 的值和 self.tabBarItem.title 的值都是@"123"

问题3

UIBarItem和 UIBarButtonItem 还有 UINavigationItem的关系
UIBarItem类是一个可以放置在Bar之上的所有小控件类的抽象类。继承了该基类所有子类在外观上类似于一个Button,它们都有一个标题,图片,动作以及目标.
** UIBarButtonItem继承自UIBarItem,专门用来放在UIToolbar 或者 UINavigationBar的特殊button.基本行为跟button是一样的。
** UINavigationItem
包含了当前页面导航栏上需要显示的全部信息,包括:
title, prompt, titleView, leftBarButtonItem, leftBarButtonItems, rightBarButtonItem, rightBarButtonItems, backBarButonItem

问题4

navigationBar的各种颜色设置

//设置标题
self.navigationItem.title = @"Hello World";
//设置左边的按钮
self.navigationItem.leftBarButtonItem = item1;
//设置右面的按钮 们
self.navigationItem.rightBarButtonItems = @[item1,item2];

//设置leftItems/rightItems的颜色
self.navigationController.navigationBar.tintColor = [UIColor redColor];
//设置NavigationBar背景颜色
self.navigationController.navigationBar.barTintColor = [UIColor greenColor];
//设置NavigationBar背景图片
[self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
//设置title的文字颜色
self.navigationController.navigationBar.titleTextAttributes @{NSForegroundColorAttributeName:[UIColor yellowColor]};

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