自定义导航栏，随着tableView滚动显示和隐藏
一、介绍
自定义导航栏是APP中很常用的一个功能，通过自定义可以灵活的实现动画隐藏和显示效果。虽然处理系统的导航栏也可以实现，但是这个是有弊端的，因为系统导航栏是全局的，在任何一个地方去修改导航栏内部的结构，其他地方都会改变，需要再次去特殊处理，否则很容易出现不可预知的bug。此时，自定义是最好的选择。
二、思想
（1）在控制器将要显示时，隐藏系统的导航栏，显示自定义的导航栏
（2）在控制器将要消失时，显示系统的导航栏，隐藏自定义的导航栏
（3）重写scrollView的代理方法，监测ContentOffst.y偏移，动态控制自定义的导航栏的可见性
三、定义
@interface XYQNavigationBar : UIView
@property (copy , nonatomic)void(^clickLeftItemBlock)(); // click left button block
@property (copy , nonatomic)void(^clickRightItemBlock)(); // click right button block
@property (copy , nonatomic)NSString *title; // title
@property (assign,nonatomic)UIColor *titleColor; // title color
@property (strong,nonatomic)UIColor *navBackgroundColor;// navagationBar background color
@property (strong,nonatomic)UIImage *navBackgroundImage;// navigationBar background image
+(instancetype)createCustomNavigationBar; //create navigationBar
-(void)showCustomNavigationBar:(BOOL)show; //set navigationBar hide, defalut is NO
-(void)setupBgImageAlpha:(CGFloat)alpha animation:(NSTimeInterval)duration compeleteBlock:(void (^)())compeleteBlock;// navigationBar background image alpha
-(void)setupBgColorAlpha:(CGFloat)alpha animation:(NSTimeInterval)duration compeleteBlock:(void (^)())compeleteBlock;// navigationBar background color alpha
-(void)setLftItemImage:(NSString *)imgName leftItemtitle:(NSString *)leftItemtitle textColor:(UIColor *)color; // navigationBar left button has title and image
-(void)setRightItemImage:(NSString *)imgName rightItemtitle:(NSString *)rightItemtitle textColor:(UIColor *)color;// navigationBar right button has title and image
-(void)setLeftItemImage:(NSString *)imgName; // navigationBar left button only has image
-(void)setRightItemImage:(NSString *)imgName; // navigationBar right button only has image
@end
四、实现
（）创建
- (void)viewDidLoad {
[super viewDidLoad];
//init
self.tableView = [[UITableView alloc] initWithFrame:self.view.bounds];
self.tableView.dataSource = self;
self.tableView.delegate = self;
self.navigationBar = [XYQNavigationBar createCustomNavigationBar];
//update（此处可以*改变导航栏的属性值）
self.navigationBar.title = @"自定义导航栏";
//block
__weak typeof(self) weakSelf = self;
self.navigationBar.clickLeftItemBlock = ^(){
[weakSelf.navigationController popViewControllerAnimated:YES];
};
self.navigationBar.clickRightItemBlock = ^(){
[weakSelf.navigationController pushViewController:[[SecondViewController alloc] init] animated:YES];
};
// add
[self.view addSubview:self.tableView];
[self.view addSubview:self.navigationBar];
}
（）显示
-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
//hide system navigationBar
[self.navigationController setNavigationBarHidden:YES animated:YES];
//show custom navigationBar
[self.navigationBar showCustomNavigationBar:YES];
}
（）隐藏
-(void)viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
//show system navigationBar
[self.navigationController setNavigationBarHidden:NO animated:YES];
//hide custom navigationBar
[self.navigationBar showCustomNavigationBar:NO];
}
（）监测
#pragma mark - public methods
// animation show or hide navigationbar
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
CGFloat offsetY = scrollView.contentOffset.y;
CGFloat colorOffset = offsetY / 64.0;
colorOffset = colorOffset > ? : colorOffset;
//method 1 : change backgrundViewImage alpha
[self.navigationBar setupBgImageAlpha:colorOffset animation:0.4 compeleteBlock:nil];
//method 2 : change backgrundViewColor alpha
//[self.navigationBar setupBgColorAlpha:colorOffset animation:0.4 compeleteBlock:nil];
}
五、效果
六、下载