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

#define XTSegmentControlHspace (12)- (void)initItemsWithTitleArray:(NSArray *)titleArray{    _itemFrames = @[].mutableCopy;    _items = @[].mutableCopy;    float y = 0;    float height = CGRectGetHeight(self.bounds);    NSDictionary *attributes = @{NSFontAttributeName: [UIFont systemFontOfSize:XTSegmentControlItemFont]};        NSObject *obj = [titleArray firstObject];    if ([obj isKindOfClass:[NSString class]]) {        for (int i = 0; i < titleArray.count; i++) {            NSString *title = titleArray[i];            CGSize size = [title sizeWithAttributes:attributes];                        float x = i > 0 ? CGRectGetMaxX([_itemFrames[i-1] CGRectValue]) : 0;            float width = 2 * XTSegmentControlHspace + size.width;            CGRect rect = CGRectMake(x, y, width, height);            [_itemFrames addObject:[NSValue valueWithCGRect:rect]];        }                for (int i = 0; i < titleArray.count; i++) {            CGRect rect = [_itemFrames[i] CGRectValue];            NSString *title = titleArray[i];            XTSegmentControlItem *item = [[XTSegmentControlItem alloc] initWithFrame:rect title:title type:XTSegmentControlItemTypeTitle];            if (i == 0) {                [item setSelected:YES];            }            [_items addObject:item];            [_contentView addSubview:item];        }    }        [_contentView setContentSize:CGSizeMake(CGRectGetMaxX([[_itemFrames lastObject] CGRectValue]), CGRectGetHeight(self.bounds))];    self.currentIndex = 0;    [self selectIndex:0];}- (void)addRedLine{    if (!_lineView) {        CGRect rect = [_itemFrames[0] CGRectValue];        _lineView = [[UIView alloc] initWithFrame:CGRectMake(XTSegmentControlHspace, CGRectGetHeight(rect) - XTSegmentControlLineHeight, CGRectGetWidth(rect) - 2 * XTSegmentControlHspace, XTSegmentControlLineHeight)];        _lineView.backgroundColor = [UIColor colorWithHexString:@"0x3bbd79"];        [_contentView addSubview:_lineView];                UIView *bottomLineView = [[UIView alloc] initWithFrame:CGRectMake(0, CGRectGetHeight(rect)-0.5, CGRectGetWidth(self.bounds), 0.5)];        bottomLineView.backgroundColor = [UIColor colorWithHexString:@"0xc8c7cc"];        [self addSubview:bottomLineView];    }}

@interface XTSegmentControl : UIView@property (nonatomic) NSInteger currentIndex;- (instancetype)initWithFrame:(CGRect)frame Items:(NSArray *)titleItem delegate:(id <XTSegmentControlDelegate>)delegate;- (instancetype)initWithFrame:(CGRect)frame Items:(NSArray *)titleItem selectedBlock:(XTSegmentControlBlock)selectedHandle;- (void)selectIndex:(NSInteger)index;- (void)moveIndexWithProgress:(float)progress;- (void)endMoveIndex:(NSInteger)index;- (void)setScrollOffset:(NSInteger)index;@end

- (UIView *)carousel:(iCarousel *)carousel viewForItemAtIndex:(NSUInteger)index reusingView:(UIView *)view{    [_mySegmentControl setScrollOffset:index];    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;}