1.网易新闻标签栏效果的实现,用个小Demo实例介绍一下:
#import "HMTMainViewController.h"
#import "HMTFirstViewController.h"
#import "HMTSecondViewController.h"
#import "HMTThirdViewController.h"
@interface HMTMainViewController () <UIScrollViewDelegate>
@property (nonatomic ,strong) HMTThirdViewController *thirdVC;
@property (nonatomic ,strong) HMTFirstViewController *firstVC;
@property (nonatomic ,strong) HMTSecondViewController *secondVC;
@property (nonatomic ,strong) UIViewController *currentVC;
//顶部滚动视图
@property (nonatomic ,strong) UIScrollView *headScrollView;
@property (nonatomic ,strong) NSArray *headArray;
@end
@implementation HMTMainViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.navigationItem.title = @"网易新闻Demo";
self.headArray = @[@"头条",@"娱乐",@"体育",@"财经",@"科技",@"NBA",@"手机"];
/**
* automaticallyAdjustsScrollViewInsets 又被这个属性坑了
* 我"UI高级"里面一篇文章着重讲了它,大家可以去看看
*/
self.automaticallyAdjustsScrollViewInsets = NO;
self.headScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 64, 320, 40)];
self.headScrollView.backgroundColor = [UIColor purpleColor];
self.headScrollView.contentSize = CGSizeMake(560, 0);
self.headScrollView.bounces = NO;
self.headScrollView.pagingEnabled = YES;
[self.view addSubview:self.headScrollView];
for (int i = 0; i < [self.headArray count]; i++) {
UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
button.frame = CGRectMake(0 + i*80, 0, 80, 40);
[button setTitle:[self.headArray objectAtIndex:i] forState:UIControlStateNormal];
button.tag = i + 100;
[button addTarget:self action:@selector(didClickHeadButtonAction:) forControlEvents:UIControlEventTouchUpInside];
[self.headScrollView addSubview:button];
}
/*
苹果新的API增加了addChildViewController方法，并且希望我们在使用addSubview时，
同时调用[self addChildViewController:child]方法将sub view对应的viewController也加到当前ViewController的管理中。
对于那些当前暂时不需要显示的subview，只通过addChildViewController把subViewController加进去；
需要显示时再调用transitionFromViewController方法。将其添加进入底层的ViewController中。
这样做的好处：
1.无疑，对页面中的逻辑更加分明了。相应的View对应相应的ViewController。
2.当某个子View没有显示时，将不会被Load，减少了内存的使用。
3.当内存紧张时，没有Load的View将被首先释放，优化了程序的内存释放机制。
*/
self.firstVC = [[HMTFirstViewController alloc] init];
[self.firstVC.view setFrame:CGRectMake(0, 104, 320, 464)];
[self addChildViewController:_firstVC];
self.secondVC = [[HMTSecondViewController alloc] init];
[self.secondVC.view setFrame:CGRectMake(0, 104, 320, 464)];
self.thirdVC = [[HMTThirdViewController alloc] init];
[self.thirdVC.view setFrame:CGRectMake(0, 104, 320, 464)];
// 默认,第一个视图(你会发现,全程就这一个用了addSubview)
[self.view addSubview:self.firstVC.view];
self.currentVC = self.firstVC;
}
- (void)didClickHeadButtonAction:(UIButton *)button
{
// 点击处于当前页面的按钮,直接跳出
if ((self.currentVC == self.firstVC && button.tag == 100)||(self.currentVC == self.secondVC && button.tag == 101.)) {
return;
}else{
// 展示2个,其余一样,自行补全噢
switch (button.tag) {
case 100:
[self replaceController:self.currentVC newController:self.firstVC];
break;
case 101:
[self replaceController:self.currentVC newController:self.secondVC];
break;
case 102:
//.......
break;
case 103:
//.......
break;
case 104:
//.......
break;
case 105:
//.......
break;
case 106:
//.......
break;
//.......
default:
break;
}
}
}
// 切换各个标签内容
- (void)replaceController:(UIViewController *)oldController newController:(UIViewController *)newController
{
/**
* 着重介绍一下它
* transitionFromViewController:toViewController:duration:options:animations:completion:
* fromViewController 当前显示在父视图控制器中的子视图控制器
* toViewController 将要显示的姿势图控制器
* duration 动画时间(这个属性,old friend 了 O(∩_∩)O)
* options 动画效果(渐变,从下往上等等,具体查看API)
* animations 转换过程中得动画
* completion 转换完成
*/
[self addChildViewController:newController];
[self transitionFromViewController:oldController toViewController:newController duration:2.0 options:UIViewAnimationOptionTransitionCrossDissolve animations:nil completion:^(BOOL finished) {
if (finished) {
[newController didMoveToParentViewController:self];
[oldController willMoveToParentViewController:nil];
[oldController removeFromParentViewController];
self.currentVC = newController;
}else{
self.currentVC = oldController;
}
}];
}
2.示例源码：
用addChildViewController，一个ViewController可以添加多个子ViewController，但是这些子ViewController
只有一个是显示到父视图中的，可以通过transitionFromViewController:
toViewController:duration:options:animations:completion:这个方法转换显示的子视图。同时加入相应的动画。
//在parent view controller 中添加 child view controller
FirstViewController *firstViewController=[[FirstViewController alloc] initWithNibName:@"FirstViewController" bundle:nil];
[self addChildViewController:firstViewController];
SecondViewController *secondViewController=[[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
[self addChildViewController:secondViewController];
ThirdViewController *thirdViewController=[[ThirdViewController alloc] initWithNibName:@"ThirdViewController" bundle:nil];
[self addChildViewController:thirdViewController];
[self.view addSubview:thirdViewController.view];
//addChildViewController回调用[childc willMoveToParentViewController:self] ，
//但是不会调用didMoveToParentViewController，所以需要显示调用
[thirdViewController didMoveToParentViewController:self];
currentViewController=thirdViewController;
//切换child view controller
[self transitionFromViewController:currentViewController toViewController:firstViewController duration:4 options:UIViewAnimationOptionTransitionFlipFromLeft animations:^{
} completion:^(BOOL finished) {
//......
}];
currentViewController=firstViewController;
//移除child view controller
//removeFromParentViewController在移除child前不会调用
//[self willMoveToParentViewController:nil]，所以需要显示调用
[currentViewController willMoveToParentViewController:nil];
[currentViewController removeFromSuperview];
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