默认情况下控制器标题过长导致无法全部显示, 解决此问题就要让标题可以滚动.

实现很简单, 只要把navigationItem.titleView赋值一个UIScrollView, 并且让这个UIScrollView自动滚动就可以了.

一. 定义一个创建一个继承与UIScrollerView的类

  1. 头文件

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    @interface CTScrollTitleView : UIScrollView

      /** 文字 */
    @property (nonatomic, strong, readonly) NSString *title;

    /** 实例化对象 */
    + (instancetype)titleViewWithTitle:(NSString *)title;
    - (instancetype)initWithTitle:(NSString *)title;

    @end

  2. .m文件

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    @implementation CTScrollTitleView

    + (instancetype)titleViewWithTitle:(NSString *)title
    {
       return [[self alloc] initWithTitle:title];
    }

    - (instancetype)initWithTitle:(NSString *)title
    {
       if (title==nil) return nil;

       if (self = [super initWithFrame:CGRectZero]) {

           _title = title;
           self.frame = CGRectMake(0, 0, screenWidth-128, 44);
           self.scrollEnabled = false;
           self.showsVerticalScrollIndicator = false;
           self.showsHorizontalScrollIndicator = false;

           UILabel *label = [UILabel new];
           label.font = [UIFont boldSystemFontOfSize:16];
           label.frame = self.bounds;
           label.textAlignment = NSTextAlignmentCenter;
           label.text = title;
           [self addSubview: label];

         // 计算文字的宽度
       CGFloat width = [label.text boundingRectWithSize:CGSizeMake(MAXFLOAT, label.height)
                                                options:
                         NSStringDrawingTruncatesLastVisibleLine |
                         NSStringDrawingUsesLineFragmentOrigin |
                         NSStringDrawingUsesFontLeading
                                             attributes:@{NSFontAttributeName: label.font}
                                                context:nil].size.width;
         // 只有文字宽度大于scrollview的宽度才需要滚动
           if (width > self.frame.size.width) { 
               CGRect frame = label.frame;
               frame.size.width = width;
               label.frame = frame;

               CGSize contentSize = self.contentSize;
               contentSize.width = width;
               self.contentSize = contentSize;

               [self startAnimate];
           }
       }

       return self;
    }

    /** 滚动动画 */
    - (void)startAnimate {

       NSTimeInterval time = self.contentSize.width * 0.01;

       CGPoint offset = self.contentOffset;
       offset.x = self.contentSize.width - self.frame.size.width;

       __weak typeof(self)weakSelf = self;
     // 从左向右
       [UIView animateWithDuration:time 
                             delay:2.0 
                           options:0 		
                        animations:^{
           weakSelf.contentOffset = offset;
                      } completion:^(BOOL finished) {
           // 从右向左
           [UIView animateWithDuration:time 
                                 delay:2.0
                               options:0 															  animations:^{
              weakSelf.contentOffset = CGPointZero;

                          } completion:^(BOOL finished) {
               [weakSelf startAnimate];
           }];

       }];
    }

    - (void)dealloc{
       NSLog(@"%s", __func__)
    }

二. 使用

  1. 导入头文件

  2. 实例化CTScrollTitleView并赋值给navigationItem.titleView

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    self.navigationItem.titleView = [CTScrollTitleView titleViewWithTitle:@"标题标题标题标题标题标题标题标题"];

三. 简化版

  1. 为了开发方便, 比如直接谁用 self.scrollTitle = @”标题标题标题标题标题标题标题标题标题标题”, 可做以下处理

  2. 创建UIViewController分类: UIViewController+ScrollTitle.h

  3. 在头文件声明

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    @interface UIViewController (ScrollTitle)
    /** 滚动标题 */
    @property (nonatomic, strong) NSString *zy_scrollTitle;

    @end

  4. .m文件实现

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    #import <objc/runtime.h>
    #import "CTScrollTitleView.h"

    @interface UIViewController()
    @property (nonatomic, weak) CTScrollTitleView *zy_titleView;
    @end

    @implementation UIViewController (ScrollTitle)

    - (void)setZy_scrollTitle:(NSString *)zy_scrollTitle
    {
        CTScrollTitleView *titleView = [CTScrollTitleView titleViewWithTitle:zy_scrollTitle];
        self.navigationItem.titleView = titleView;
        self.zy_titleView = titleView;
    }
    - (NSString *)zy_scrollTitle
    {
        return self.zy_titleView.title;
    }

    static char ZYScrollTitleViewKey = '\0';
    - (void)setZy_titleView:(CTScrollTitleView *)zy_titleView
    {
        objc_setAssociatedObject(self, &ZYScrollTitleViewKey, zy_titleView, OBJC_ASSOCIATION_ASSIGN);
    }

    - (CTScrollTitleView *)zy_titleView
    {
        return objc_getAssociatedObject(self, &ZYScrollTitleViewKey);
    }

    ​

  5. 直接使用self.zy_scrollTitle即可