选项卡的实现原理

        UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 64, screen_width, 40)];
        scrollView.pagingEnabled = NO;
        scrollView.alwaysBounceHorizontal = YES;
        scrollView.showsHorizontalScrollIndicator = NO;
        scrollView.showsVerticalScrollIndicator = NO;
        scrollView.backgroundColor = RGB(246, 246, 246);
        [self.view addSubview:scrollView];
        
        float btnWidth = 60;
        
        for (int i = 0; i < self.cateNameArray.count; i++) {
            UIButton *nameBtn = [UIButton buttonWithType:UIButtonTypeCustom];
            nameBtn.frame = CGRectMake(btnWidth*i, 0, btnWidth, 40);
            nameBtn.tag = 10+i;
            nameBtn.font = [UIFont systemFontOfSize:13];
            [nameBtn setTitle:self.cateNameArray[i] forState:UIControlStateNormal];
            [nameBtn setTitleColor:navigationBarColor forState:UIControlStateSelected];
            [nameBtn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
            [nameBtn addTarget:self action:@selector(OnTapNameBtn:) forControlEvents:UIControlEventTouchUpInside];
            [scrollView addSubview:nameBtn];
            if (i == 0) {
//                nameBtn.selected = YES;
                _lineView = [[UIView alloc] initWithFrame:CGRectMake(nameBtn.center.x-20, 38, 40, 2)];
                _lineView.backgroundColor = navigationBarColor;
                [scrollView addSubview:_lineView];
            }
        }
        scrollView.contentSize = CGSizeMake(self.cateNameArray.count*btnWidth, 0);

-(void)OnTapNameBtn:(UIButton *)sender{
    NSInteger index = sender.tag - 10;
    if (index == _currentIndex) {
        return;
    }
    _currentIndex = index;
    _cateid = _cateIDArray[index];
    _page = 1;
    [UIView animateWithDuration:0.5 animations:^{
        _lineView.center = CGPointMake(sender.center.x, 39);
    }];
    //刷新数据
    [self.tableView.gifHeader beginRefreshing];
}

#import <UIKit/UIKit.h>
#import "oldChildVewController.h"
#import "ChildViewController.h"
#import "newChildVewController.h"
#import "XTSegmentControl.h"
#import "iCarousel.h"
#import "Masonry.h"

@interface ViewController : UIViewController<iCarouselDataSource, iCarouselDelegate>


@end

#import "ViewController.h"


#define kScreen_Height [UIScreen mainScreen].bounds.size.height
#define kScreen_Width [UIScreen mainScreen].bounds.size.width
#define kMySegmentControl_Height 44.0


@interface ViewController ()
@property (strong, nonatomic) NSMutableDictionary *myProActivitiesDict;
@property (strong, nonatomic) XTSegmentControl *mySegmentControl;
@property (strong, nonatomic) NSArray *titlesArray;
@property (strong, nonatomic) iCarousel *myCarousel;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.backgroundColor=[UIColor whiteColor];
    CGRect frame=self.view.bounds;
    self.myCarousel = ({
        iCarousel *icarousel = [[iCarousel alloc] initWithFrame:frame];
        icarousel.dataSource = self;
        icarousel.delegate = self;
        icarousel.decelerationRate = 1.0;
        icarousel.scrollSpeed = 1.0;
        icarousel.type = iCarouselTypeLinear;
        icarousel.pagingEnabled = YES;
        icarousel.clipsToBounds = YES;
        icarousel.bounceDistance = 0.2;
        [self.view addSubview:icarousel];
        [icarousel mas_makeConstraints:^(MASConstraintMaker *make) {
            make.edges.equalTo(self.view).insets(UIEdgeInsetsMake(kMySegmentControl_Height, 0, 0, 0));
        }];
        icarousel;
    });
    
    //添加滑块
    __weak typeof(_myCarousel) weakCarousel = _myCarousel;
    
    self.mySegmentControl = [[XTSegmentControl alloc] initWithFrame:CGRectMake(0, 0, kScreen_Width, kMySegmentControl_Height) Items:self.titlesArray selectedBlock:^(NSInteger index) {
        [weakCarousel scrollToItemAtIndex:index animated:NO];
    }];
    
    [self.view addSubview:self.mySegmentControl];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

#pragma mark - Getter/Setter
- (NSArray*)titlesArray
{
    if (nil == _titlesArray) {
            _titlesArray = @[@"全部", @"任务", @"讨论", @"文档", @"代码", @"其他"];
    }
    return _titlesArray;
}
#pragma mark iCarousel M
- (NSUInteger)numberOfItemsInCarousel:(iCarousel *)carousel{
    return [self.titlesArray count];
}
- (UIView *)carousel:(iCarousel *)carousel viewForItemAtIndex:(NSUInteger)index reusingView:(UIView *)view{
    UIViewController *childContrll;
    switch (index) {
        case 0:
        {
            childContrll=[[ChildViewController alloc]init];
            
            break;
        }
        case 1:
        {
            childContrll=[[oldChildVewController alloc]init];
            
            break;
        }
        default:
            childContrll=[[newChildVewController alloc]init];
            break;
    }
    return childContrll.view;
}

- (void)carouselDidScroll:(iCarousel *)carousel{
    if (_mySegmentControl) {
        float offset = carousel.scrollOffset;
        if (offset > 0) {
            [_mySegmentControl moveIndexWithProgress:offset];
        }
    }
}

- (void)carouselCurrentItemIndexDidChange:(iCarousel *)carousel{
    if (_mySegmentControl) {
        _mySegmentControl.currentIndex = carousel.currentItemIndex;
    }
}

@end