导航栏下面添加的view会出现布局错误，解决办法先记下来。
将添加的视图移到导航栏的下面
self.edgesForExtendedLayout = UIRectEdgeNone;
self.navigationController.navigationBar.translucent = NO;//两种都可以
这种方式解决的话，注意frame的y值的设置：
XXTitleView *titleView = [[XXTitleView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 40)];
还有一种方式，避免scrollView的自动布局
self.automaticallyAdjustsScrollViewInsets = NO;
这种方式解决，frame的y值要留一个状态栏和导航栏的距离：
XXTitleView *titleView = [[XXTitleView alloc] initWithFrame:CGRectMake(0, 64, self.view.frame.size.width, 40)];
还需注意：
（1）设置button的文字,不要使用button.titleLabel.text,应该用set方法。
（2）不要使用sizetofit，容易出错（原因还没想到，这里只是提醒自己。
（3）用boundingRectWithSize方法根据文字计算button的宽度，一定记得要把button的宽度多设一点（至少多设2），不能刚刚好，要不然显示不全。
下面是显示的导航栏的demo，点击某个按钮，如果不是最靠左和最靠右，则将其显示在屏幕中间。下面加一个下划线（下划线的效果是直接出现，想优化成滑动的效果，且留作下次的任务）。主要代码如下：
AppDelegate.m文件
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
self.window = [[UIWindow alloc] init];
self.window.backgroundColor = [UIColor whiteColor];
XXHomeViewController *homeVC = [[XXHomeViewController alloc] init];
self.window.rootViewController = [[UINavigationController alloc] initWithRootViewController:homeVC];
//self.window.rootViewController = homeVC;
[self.window makeKeyAndVisible];
return YES;
}
XXHomeViewController.m文件
#import "XXHomeViewController.h"
#import "XXTitleView.h"
@interface XXHomeViewController ()
@property (strong, nonatomic) NSArray *titleArray;
@end
@implementation XXHomeViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.title = @"标题";
//self.edgesForExtendedLayout = UIRectEdgeNone;
self.titleArray = @[@"百度",@"腾讯",@"阿里巴巴",@"微博",@"美团",@"百思不得姐",@"应用宝",@"苹果",@"搞笑视频",@"小说"];
self.automaticallyAdjustsScrollViewInsets = NO;
XXTitleView *titleView = [[XXTitleView alloc] initWithFrame:CGRectMake(0, 64, self.view.frame.size.width, 40)];
titleView.titleArray = self.titleArray;
[self.view addSubview:titleView];
}
@end
XXTitleView.h文件
#import <UIKit/UIKit.h>
@interface XXTitleView : UIView
@property (strong, nonatomic) NSArray *titleArray;
@end
XXTitleView.m文件
#import "XXTitleView.h"
//#import "UIView+Extension.h"
@interface XXTitleView ()
//保存所有的button
@property (strong, nonatomic) NSMutableArray *titleButtons;
//保存所有的下划线
@property (strong, nonatomic) NSMutableArray *titleLines;
//titleView
@property (weak, nonatomic) UIScrollView *titleView;
//记录上一个按钮的宽度
@property(nonatomic, assign)CGFloat lastbtnW;
//记录当前选中的按钮
@property (weak, nonatomic) UIButton *currentButton;
@end
@implementation XXTitleView
#pragma mark -- 懒加载
- (NSMutableArray *)titleButtons{
if(_titleButtons == nil){
_titleButtons = [NSMutableArray array];
}
return _titleButtons;
}
- (NSMutableArray *)titleLines{
if (_titleLines == nil) {
_titleLines = [NSMutableArray array];
}
return _titleLines;
}
#pragma mark -- set方法
- (void)setTitleArray:(NSArray *)titleArray{
if(_titleArray == nil){
_titleArray = titleArray;
}
[self setupTitleView];
}
#pragma mark -- 初始化
- (instancetype)initWithFrame:(CGRect)frame{
if (self = [super initWithFrame:frame]) {
//初始化界面
}
return self;
}
- (void)setupTitleView{
//NSLog(@"我是setupTitleView");
//1.创建titileView
UIScrollView *titleView = [[UIScrollView alloc] init];
titleView.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
titleView.showsVerticalScrollIndicator = NO;
titleView.showsHorizontalScrollIndicator = NO;
titleView.bounces = NO;
titleView.backgroundColor = [UIColor lightGrayColor];
titleView.delegate = self;
[self addSubview:titleView];
self.titleView = titleView;
//2.创建8-10个按钮，并将其加入到titleView
float btnMargin = 5;
float btnX = 0;
for (int i = 0; i < self.titleArray.count; i++) {
//2.1 根据文字计算button的宽度
NSDictionary *arributes = @{NSFontAttributeName:[UIFont boldSystemFontOfSize:14]};
NSStringDrawingOptions option = NSStringDrawingUsesFontLeading | NSStringDrawingUsesDeviceMetrics | NSStringDrawingUsesLineFragmentOrigin;
CGSize titleSize = [self.titleArray[i] boundingRectWithSize:CGSizeMake(MAXFLOAT, MAXFLOAT) options:option attributes:arributes context:nil].size;
CGFloat textW = titleSize.width + 2 * btnMargin;
self.lastbtnW = textW;
btnX = btnX + textW;
//NSLog(@"btnX = %f",btnX);
//2.2 创建button
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.tag = i;
//button.backgroundColor = [UIColor colorWithRed:arc4random_uniform(255)/255.0 green:arc4random_uniform(255)/255.0 blue:arc4random_uniform(255)/255.0 alpha:1];
button.frame = CGRectMake(btnX - self.lastbtnW, 0, textW, self.frame.size.height);
//2.3 设置button的文字,不要使用button.titleLabel.text,不要使用sizetofit
[button setTitle:self.titleArray[i] forState:UIControlStateNormal];
[button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
//[button setTitleColor:[UIColor whiteColor] forState:UIControlStateHighlighted];
[button setTitleColor:[UIColor whiteColor] forState:UIControlStateSelected];
button.titleLabel.font = [UIFont boldSystemFontOfSize:14];
//2.4 添加button到视图中
[self.titleButtons addObject:button];
[self.titleView addSubview:button];
//2.5添加button点击事件
[button addTarget:self action:@selector(clickButton:) forControlEvents:UIControlEventTouchUpInside];
//创建一根下划线，添加到button中
CGFloat lineW = titleSize.width;
CGFloat lineH = 3;
CGFloat lineX = 0.5 * (button.frame.size.width - lineW);
CGFloat lineY = button.frame.size.height - lineH;
UIView *line = [[UIView alloc] initWithFrame:CGRectMake(lineX, lineY, lineW, lineH)];
line.tag = i;
line.backgroundColor = [UIColor redColor];
line.hidden = YES;
[self.titleLines addObject:line];
[button addSubview:line];
// NSLog(@"button : %@",NSStringFromCGRect(button.frame));
// NSLog(@"line : %@",NSStringFromCGRect(line.frame));
//3.设置titleView的contentSize
self.titleView.contentSize = CGSizeMake(CGRectGetMaxX(button.frame), 0);
}
}
- (void)clickButton:(UIButton *)button{
NSLog(@"%d",button.tag);
//取出当前的下划线，并将其hidden设置为no
self.currentButton.selected = NO;
UIView *selectedLine = self.titleLines[self.currentButton.tag];
selectedLine.hidden = YES;
button.selected = YES;
self.currentButton = button;
UIView *currentLine = self.titleLines[self.currentButton.tag];
currentLine.hidden = NO;
//获取当前按钮的x值,只有当第三种情况下才需要改变scrollview的偏移
//1.获取到当前点击按钮的x值，加上此按钮的宽度与中心作比较，如果小于宽度的中心，将titleVIew的偏移量设置为0
//2.获取到当前点击按钮的x值，减去此按钮的宽度与中心作比较，如果大于宽度的中心，将titleVIew的x偏移量设置为contenSize-屏幕的宽度
//3.其他情况。按钮相对于屏幕的位移+此按钮的一半宽度与屏幕中心作对比。
//获取当前按钮的x值
CGFloat buttonX = CGRectGetMaxX(self.currentButton.frame) - self.currentButton.frame.size.width;
//获取当前scrollView的x偏移量
CGFloat offsetX = self.titleView.contentOffset.x;
//取得当前按钮此时相对于屏幕的值
CGFloat widthToScreen = buttonX - offsetX;
//获取屏幕宽度的一半
CGFloat halfWidth = [[UIScreen mainScreen] bounds].size.width * 0.5;
//当前按钮的x值加上按钮的一半宽度
CGFloat buttonXaddHalfWidth = widthToScreen + 0.5 * self.currentButton.frame.size.width;
if ((buttonX + 0.5 * self.currentButton.frame.size.width) < halfWidth) {
//button的x值+button一半的宽度小于屏幕宽度的一半
//将titleVIew的偏移量设置为0
[self.titleView setContentOffset:CGPointMake(0, 0) animated:YES];
}
else if ((self.titleView.contentSize.width - buttonX - 0.5 * self.currentButton.frame.size.width < halfWidth)){
//button的x值-button一半的宽度大于屏幕宽度的一半
//将titleVIew的x偏移量设置为contenSize-屏幕的宽度
CGFloat titleViewOffsetX = self.titleView.contentSize.width - 2 * halfWidth;
[self.titleView setContentOffset:CGPointMake(titleViewOffsetX, 0) animated:YES];
}
else{
//相对于屏幕的宽度+按钮宽度的一半<屏幕的中心， 则向右移一点（即titleVIew的x偏移量减小）
//相对于屏幕的宽度+按钮宽度的一半>屏幕的中心， 则向左移一点（即titleVIew的x偏移量增大）
//改变偏移量
CGFloat titleViewOffsetX = self.titleView.contentOffset.x - (halfWidth - buttonXaddHalfWidth);
[self.titleView setContentOffset:CGPointMake(titleViewOffsetX, 0) animated:YES];
}
}
@end
屏幕快照 2016-12-29 下午8.22.14.png
