iOS 超 Easy 实现渐变导航栏

2022-12-19 08:03:40

接着上周的项目, 在上周我别出心裁的在自定义TabbarController中加入了自定义转场动画, 受到了大家广泛的喜爱, 再次表示感激, 今天我们继续实现LifestyleViewController的第二个功能渐变导航栏!!

渐变导航栏, 现在很多项目里都有这个功能, 我们就把这个功能集成到我们的项目中来; 根据设计图纸需求, 我们需要在轮播图下面有一个搜索栏, 搜索栏根据滑动偏移到导航栏之上.

具体怎么实现呢, Easy啦~ 不急,我们一步一步来.

创建搜索栏Cell

首先打开我们的项目先在轮播图Cell下创建一个搜索栏Cell 并添加子控件.

- (UIImageView *)hotSpotsImageView {

if (!_hotSpotsImageView) {

_hotSpotsImageView = [UIImageView new];

_hotSpotsImageView.image = [UIImage imageNamed:@"Hot Spots"];

}

return _hotSpotsImageView;

}

- (void)layoutSubviews {

[super layoutSubviews];

CGFloat padding = kSpace;

CGFloat hotSpotsImageViewX = padding;

CGFloat hotSpotsImageViewW = 90;

CGFloat hotSpotsImageViewH = 20;

CGFloat hotSpotsImageViewY = self.height - hotSpotsImageViewH - 5;

self.hotSpotsImageView.frame = CGRectMake(hotSpotsImageViewX, hotSpotsImageViewY, hotSpotsImageViewW, hotSpotsImageViewH);

}

这时你可能会问为什么不在Cell中添加TextField之类的, 由于我们的效果,之后再向您揭晓;

控制器多Cell设计

这时回到控制器, 但是控制器中不止一种Cell, 我们怎么来设计呢?? 我的实现方法是KeysArr, 那什么是KeysArr呢,我们来看代码.

首先我们需要创建一个全局类 (这个写法和上周的投机流自定义转场有异曲同工之妙)

创建全局类

全局类中的每一个Key对应着你的一个Cell

extern NSString * const kSQLifestyleBannerKey;

extern NSString * const kSQLifestyleSearchKey;

NSString * const kSQLifestyleBannerKey = @"轮播图";

NSString * const kSQLifestyleSearchKey = @"热点";

keys数组

接着我们创建一个数组来持有这些key;

@property (nonatomic,strong) NSArray * keysArr;

- (NSArray *)keysArr {

if (!_keysArr) {

_keysArr = @[kSQLifestyleBannerKey,

kSQLifestyleSearchKey];

}

return _keysArr;

}

Tableview delegate mothod

最后在代理方法中进行判断

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

return self.keysArr.count;

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

NSString * const key = self.keysArr[indexPath.row];

if (key == kSQLifestyleBannerKey) {

SQLifestyleBannerCell * cell = [SQLifestyleBannerCell cellWithTableView:tableView];

return cell;

}

if (key == kSQLifestyleSearchKey) {

SQLifestyleSearchCell * cell = [SQLifestyleSearchCell cellWithTableView:tableView];

return cell;

}

return nil;

}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {

NSString * const key = self.keysArr[indexPath.row];

if (key == kSQLifestyleBannerKey) {

return [SQLifestyleBannerCell cellHeight];

}

if (key == kSQLifestyleSearchKey) {

return [SQLifestyleSearchCell cellHeight];

}

return 0;

}

这样当不需要某个cell显示的时候,只需要将keys从KeysArr中移除即可, 是不是很方便!!

创建搜索栏View

这里需要提醒大家的一点, 当你在自定义View的时候最好要实现initWithFrame和initWithCoder两个方法, 这样无论是用纯代码还是Xib,Storyboard使用自定义View时都能够直接加载!!

- (instancetype)initWithFrame:(CGRect)frame {

self = [super initWithFrame:frame];

if (self) {

[self setupSubviews];

}

return self;

}

- (instancetype)initWithCoder:(NSCoder *)coder {

self = [super initWithCoder:coder];

if (self) {

[self setupSubviews];

}

return self;

}

- (UITextField *)searchBarTextField {

if (!_searchBarTextField) {

_searchBarTextField = [UITextField new];

_searchBarTextField.backgroundColor = [UIColor whiteColor];

_searchBarTextField.layer.borderColor = KC05_dddddd.CGColor;

_searchBarTextField.layer.borderWidth = 0.5f;

_searchBarTextField.layer.cornerRadius = 5;

_searchBarTextField.layer.masksToBounds= YES;

_searchBarTextField.placeholder = @"Searching for something new";

_searchBarTextField.leftView = self.magnifierImageView;

_searchBarTextField.leftViewMode = UITextFieldViewModeAlways;

[_searchBarTextField setValue:KC04_999999 forKeyPath:@"placeholderLabel.textColor"];

}

return _searchBarTextField;

}

- (UIImageView *)magnifierImageView {

if (!_magnifierImageView) {

_magnifierImageView = [UIImageView new];

_magnifierImageView.image = [UIImage imageNamed:@"fa-search"];

_magnifierImageView.frame = CGRectMake(0, 0, 34, 34);

_magnifierImageView.contentMode = UIViewContentModeCenter;

}

return _magnifierImageView;

}

- (void)setupSubviews {

[self addSubview:self.searchBarTextField];

}

- (void)layoutSubviews {

[super layoutSubviews];

CGFloat searchBarTextFieldX = 0;

CGFloat searchBarTextFieldY = 0;

CGFloat searchBarTextFieldW = self.width;

CGFloat searchBarTextFieldH = 34;

self.searchBarTextField.frame = CGRectMake(searchBarTextFieldX, searchBarTextFieldY, searchBarTextFieldW, searchBarTextFieldH);

}

实现位移渐变

重于到今天的重头戏了, 我们来实现位移渐变!! 上面的自定义View 我们并不是将其添加到Cell之中, 而是将他添加到navigationController.view之上!!

创建两个自定义View

@property (nonatomic,strong) SQLifestyleSearchBarView * titleView;

@property (nonatomic,strong) SQLifestyleSearchBarView * searchBarView;

- (SQLifestyleSearchBarView *)titleView {

if (!_titleView) {

_titleView = [SQLifestyleSearchBarView new];

_titleView.frame = self.navigationController.navigationBar.frame;

}

return _titleView;

}

- (SQLifestyleSearchBarView *)searchBarView {

if (!_searchBarView) {

_searchBarView = [SQLifestyleSearchBarView new];

}

return _searchBarView;

}

其中一个的frame = self.navigationController.navigationBar.frame

并将其添加到titleView中!! 另一个将其加载navigationController.view中!! 并在viewWillLayoutSubviews中设置布局!!

- (void)loadView {

[super loadView];

[self.navigationItem setTitleView:self.titleView];

[self.navigationController.navigationBar setBackgroundImage:[UIImage imageWithColor:[UIColor clearColor]] forBarMetrics:UIBarMetricsDefault];

[self.navigationController.navigationBar setShadowImage:[UIImage imageWithColor:[UIColor clearColor]]];

}

- (void)viewDidLoad {

[super viewDidLoad];

[self.view addSubview:self.tableView];

[self.navigationController.view addSubview:self.searchBarView];

}

- (void)viewWillLayoutSubviews {

[super viewWillLayoutSubviews];

CGFloat searchBarViewX = kSpace;

CGFloat searchBarViewW = self.titleView.width;

CGFloat searchBarViewH = self.titleView.height;

CGFloat searchBarViewY = kScaleLength(210) + searchBarViewH - self.tableView.contentOffset.y - searchBarViewH;

self.searchBarView.frame = CGRectMake(searchBarViewX, searchBarViewY, searchBarViewW, searchBarViewH);

}

监听偏移

我们将设置导航栏背景颜色的方法从LoadView移到scrollViewDidScroll中来

这里需要和大家细说一下监听偏移渐变,其实很简单,就是一个公式而已 float alpha = 1 - (offset) - scrollView.contentOffset.y) / offset); 其中的offset 指的是y轴方向从初始值viewWillLayoutSubviews中的初始设定到导航栏的位移!!

每滑动下重新调用viewWillLayoutSubviews方法重新布局, 当其到达位移点的时候, 两个View进行交换就达到了预期的效果!!

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {

[self viewWillLayoutSubviews];

[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

float alpha = 1 - ((kScaleLength(190.5) - scrollView.contentOffset.y) / kScaleLength(190.5));

[self.navigationController.navigationBar setBackgroundImage:[UIImage imageWithColor:[KC01_57c2de colorWithAlphaComponent:alpha > 0.95f ? 0.95f : alpha]] forBarMetrics:UIBarMetricsDefault];

self.titleView.hidden = scrollView.contentOffset.y > kScaleLength(190.5) ? NO : YES;

self.searchBarView = !titleView.hidden;

}

对位移渐变的封装

上面的代码看到晕晕乎乎,讲的不清不楚!! 我们来讲这个功能封装一下, 先创建一个UIViewController的Catagory 实现方法!!

scrollView: 传入需要位移的scrollView;
titleView: 传入导航栏上的titleView;
movableView: 传入需要移动的自定义View;
offset: 传入y轴方向从初始值到导航栏的位移;
color: 传入导航栏颜色

- (void)navigationBarGradualChangeWithScrollView:(UIScrollView *)scrollView titleView:(UIView *)titleView movableView:(UIView *)movableView offset:(CGFloat)offset color:(UIColor *)color {

float alpha = 1 - ((offset - scrollView.contentOffset.y) / offset);

[self.navigationController.navigationBar setBackgroundImage:[UIImage imageWithColor:[color colorWithAlphaComponent:alpha > 0.95f ? 0.95f : alpha]] forBarMetrics:UIBarMetricsDefault];

titleView .hidden = scrollView.contentOffset.y > offset ? NO : YES;

movableView.hidden = !titleView .hidden;

}

这样我们在调用的时候就简单明了多了!! 以后做到这个功能的时候可以直接拿来用了!!

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {

[self viewWillLayoutSubviews];

[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

[self navigationBarGradualChangeWithScrollView:scrollView titleView:self.titleView movableView:self.searchBarView offset:kScaleLength(190.5) color:KC01_57c2de];

}

模拟效果

为了能看到效果我们在控制器中多加几个cell 方法很简单只要在Key数组中多加几个对象即可! 并在key == @"" 时加载如下Cell

- (NSArray *)keysArr {

if (!_keysArr) {

_keysArr = @[kSQLifestyleBannerKey,

kSQLifestyleSearchKey,

@"",@"",@"",@"",@"",

@"",@"",@"",@"",@"",

@"",@"",@"",@"",@"",

@"",@"",@"",@"",@""];

}

return _keysArr;

}

static NSString * identifier = @"cell";

UITableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:identifier];

if (!cell) {

cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];

} cell.textLabel.text = @"https://coderZsq.github.io";

return cell;

好了我们来看下显示效果吧~~

在Reaval中显示

最终显示

具体源码及SQExtension方法信息请到github上进行下载! 喜欢的朋友送下小星星哟!!

https://github.com/coderZsq/coderZsq.project.ios

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