- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen]bounds]];
ViewController *mainView = [[ViewController alloc]init];
UINavigationController *navi = [[UINavigationController alloc]initWithRootViewController:mainView];
navi.navigationBar.backgroundColor = [UIColor blueColor];
[self.window setRootViewController:navi];
[self.window makeKeyAndVisible];
return YES;
}
导航条的字体和颜色的设置self.navigationController.navigationBar.titleTextAttributes = [NSDictionary dictionaryWithObject:[UIColor whiteColor] forKey:UITextAttributeTextColor]; // --- 字体颜色
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"BJ.png"] forBarMetrics:UIBarMetricsDefault]; // — 背景色
导航条跳转页面的考虑对于用navigationcontroller来跳转页面的时候,其实是执行堆栈的进栈和出栈的操作,要想释放内存,那么在来回跳转的时候,就要考虑几个问题了1 A =>B=>C=>D,D=>A 有根视图的话 (HOME)[self.navigationController popToRootViewControllerAnimated:YES]; D=>C (每一个界面返回上一层)[self.navigationController popViewControllerAnimated:YES]; 返回到上一层,并且传递参数//此页面已经存在于self.navigationController.viewControllers中,并且是当前页面的前一页面
CViewController *cvc = [self.navigationController.viewControllers objectAtIndex:self.navigationController.viewControllers.count-
2
];
CViewController *cvc = [CViewController alloc]init];cvc.str = self.str;[self.navigationController popToViewController:cvc animated:true];返回到上一层后,上一页面显示后要接收参数,并刷新。注意此时应该在viewDidAppear中进行判断并接收传递的值-(void)viewDidAppear:(BOOL)animated{ //判断并接收返回的参数}2 A =>B=>C=>D=>E,E=>B=>C=>E因为B在之前已经出现过,不能在E中直接PUSH到B,因为那样已经是两个B了,增加内存,所以在跳转的时候,就要进行判断是否之前已经出现过B了,出现过,则直接push。这样push到的是原有的B,不会在内存中重新生成一个B了。NSArray *array = self.navigationController.viewControllers;
for (UIViewController *vc in array) {
if ([vc isKindOfClass:[BXXXViewController class]]) {
push VC;
}
或者知道每个界面的指针
[self.navigationController
popToViewController: [self.navigationController.viewControllers
objectAtIndex: ([self.navigationController.viewControllers count] -4)]
animated:YES];
在使用时,根据自己返回层的需要,只要改变一下“-4”这个数字就可以达到目的了
//=====2016年3月17日 增加导航条的变化 Xcode7.2
很多的应用现在都做到了,随着页面的滑动导航条的颜色也会发生变化,现在使用原生的导航条来体现一下基本原理。。。
*在项目属性里设置
View controller-based status bar appearance == NO 默认是YES
才可以改变导航条上20像素位置的状态栏颜色
干货:
本例使用的 UITableView 添加KVO实现监控滑动位置的变化
[_myTable addObserver:self forKeyPath:@"contentOffset" options:NSKeyValueObservingOptionNew| NSKeyValueObservingOptionInitial context:nil];
-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context{ if ([keyPath isEqualToString:@"contentOffset"]) { [self navChange]; }}
-(void)navChange{ if (_myTable.contentOffset.y <= 64) { self.navigationController.navigationBar.titleTextAttributes = [NSDictionary dictionaryWithObject:[UIColor blueColor] forKey:NSForegroundColorAttributeName]; [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"BJ1.png"] forBarMetrics:UIBarMetricsDefault]; self.title = @"初始导航条"; } else if (_myTable.contentOffset.y >= 192 ) { self.navigationController.navigationBar.titleTextAttributes = [NSDictionary dictionaryWithObject:[UIColor whiteColor] forKey:NSForegroundColorAttributeName]; [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"BJ2.png"] forBarMetrics:UIBarMetricsDefault]; self.title = @"导航条最终状态"; // 状态栏颜色为白色 [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleLightContent; }else { self.navigationController.navigationBar.titleTextAttributes = [NSDictionary dictionaryWithObject:[UIColor redColor] forKey:NSForegroundColorAttributeName]; [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"BJ3.png"] forBarMetrics:UIBarMetricsDefault]; self.title = @"导航条中间状态"; // 状态栏颜色为白色 [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleDefault; }}
上效果图 无图无真相
demo地址:https://github.com/Lian1990/NavColorRamp
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