iOS——仿网易等的简单头部滚动

仿网易的主要思想为：
1. 设置好按钮与线的宽度，
2. 将所需要的标题传入并生成按钮
3. 在点击的时候，通过计算偏移量，将自身进行偏移
4. 偏移量的设置需要注意不能小于0并且不成大于contengsize-frame的宽度

具体代码如下，可直接使用，需要注意的是需要先设置宽度，再传标题数组才可自动调整，否则会固定为默认的60

另外，BtnArr与linelabel设置为readonly比较合理，不过这里还需再进行研究，不要强制使用这两个属性即可

头文件如下：

//
//  TitleScrollView.h
//  @author 陈晋添
//
//  Created by jkc on 16/7/14.
//  Copyright © 2016年 cjt. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface TitleScrollView : UIScrollView

typedef  void(^sectionTitleViewBlock)(NSInteger num);

@property (nonatomic, strong) NSMutableArray *BtnArr;           //形成的按钮数组
@property (nonatomic, strong) UILabel *linelabel;               //底部line
@property (nonatomic, strong) sectionTitleViewBlock clickBolck; //block回调

@property (nonatomic, assign) NSInteger LineWidth;              //设置线的长度
@property (nonatomic, assign) NSInteger ButtonWidth;            //按钮的宽度

/**
 *  通过标题数组进行设置头部滚动条
 *
 *  @param array 需要加入的标题
 */
-(void)AddArrView:(NSArray*)array;

/**
 *  可直接用代码设置索引位置
 *
 *  @param index 索引位置
 */
-(void)setByIndex:(NSInteger)index;
@end

.m文件如下

//
//  TitleScrollView.m
//  @author 陈晋添
//
//  Created by jkc on 16/7/14.
//  Copyright © 2016年 cjt. All rights reserved.
//

#import "TitleScrollView.h"

#define TitleBtnTag 300         //button的tag值
@implementation TitleScrollView

-(instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {

        //初始化自身
        [self setBackgroundColor:[UIColor whiteColor]];
        self.showsHorizontalScrollIndicator = false;
        _ButtonWidth = _LineWidth = 60;

        self.linelabel = [[UILabel alloc] initWithFrame:CGRectMake(0, self.frame.size.height-1.5, _LineWidth, 1.5)];
        [self.linelabel setBackgroundColor:TintColor];
        [self addSubview:self.linelabel];
    }
    return self;
}

-(void)AddArrView:(NSArray*)array
{
    self.BtnArr = [NSMutableArray array];
    for (int i=0; i<array.count; i++) {
        //初始化所有btn
        UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(i*_ButtonWidth, 0, _ButtonWidth,34)];
        [btn addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];
        btn.titleLabel.font = [UIFont systemFontOfSize:12];
        btn.titleLabel.textAlignment = NSTextAlignmentCenter;
        [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
        [btn setTitle:array[i] forState:UIControlStateNormal];

        btn.tag = TitleBtnTag+i;

        [self addSubview:btn];
        [self.BtnArr addObject:btn];
    }
    //根据button个数设置内部大小
    [self setContentSize:CGSizeMake(array.count*_ButtonWidth, CGRectGetHeight(self.frame))];
}

-(void)click:(UIButton*)button
{
    //把所有的btn样式重置
    for (UIButton *btn in self.BtnArr) {
        btn.titleLabel.font = [UIFont systemFontOfSize:12];
        btn.titleLabel.textAlignment = NSTextAlignmentCenter;
        [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    }

    //特殊设置点击的button样式
    [button setTitleColor:[UIColor orangeColor] forState:UIControlStateNormal];

    //计算获得偏移量，
    CGFloat index = (button.tag-TitleBtnTag)*_ButtonWidth-(self.frame.size.width-_ButtonWidth)/2;
    index = index<0?0:index;
    index = index>self.contentSize.width-CGRectGetWidth(self.frame)?self.contentSize.width-CGRectGetWidth(self.frame):index;

    //动画效果偏移
    [self setContentOffset:CGPointMake(index, 0) animated:YES];
    [UIView animateWithDuration:0.3 animations:^{
        self.linelabel.frame = CGRectMake((button.tag-TitleBtnTag)*_ButtonWidth, self.frame.size.height-1, _LineWidth, 1);
    }];

    self.clickBolck(button.tag);
}

//通过外部代码直接设置索引
-(void)setByIndex:(NSInteger)nowindex
{
    UIButton *button = self.BtnArr[nowindex];
    [self click:button];
}

@end