iOS实现简单的二级菜单效果

Untitled.gif#import "ViewController.h"#import "CollectionViewCell.h"#import "CollectionSectionView.h"@interface ViewController ()<UICollectionViewDelegateFlowLayout,UICollectionViewDataSource>@property (nonatomic,strong)UICollectionView *collectionView;@property (nonatomic,copy)NSString *leftOrRight;@property (nonatomic,strong)NSIndexPath *clickIndexPath;@endstatic NSString *cellIdentifier = @"CollectionViewCell";static NSString *sectionIdentifier = @"CollectionSectionView";@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init]; flowLayout.itemSize = CGSizeMake(50, 25); flowLayout.minimumLineSpacing = 0; flowLayout.minimumInteritemSpacing = 0; flowLayout.headerReferenceSize = CGSizeMake(0, 40); flowLayout.sectionInset = UIEdgeInsetsMake(0, 0, 0, 0); self.collectionView = [[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:flowLayout]; _collectionView.backgroundColor = [UIColor whiteColor]; _collectionView.delegate = self; _collectionView.dataSource = self; [_collectionView registerClass:[CollectionViewCell class] forCellWithReuseIdentifier:cellIdentifier]; [_collectionView registerClass:[CollectionSectionView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:sectionIdentifier]; [self.view addSubview:_collectionView];}- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{ return 3;}- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{ if (self.clickIndexPath.section == section) {  if (self.clickIndexPath.section == 0 && [self.leftOrRight isEqualToString:@"left"]) {   return 3;  }  if (self.clickIndexPath.section == 0 && [self.leftOrRight isEqualToString:@"right"]) {   return 4;  }  if (self.clickIndexPath.section == 1 && [self.leftOrRight isEqualToString:@"left"]) {   return 10;  }  if (self.clickIndexPath.section == 1 && [self.leftOrRight isEqualToString:@"right"]) {   return 8;  }  if (self.clickIndexPath.section == 2 && [self.leftOrRight isEqualToString:@"left"]) {   return 33;  }  if (self.clickIndexPath.section == 2 && [self.leftOrRight isEqualToString:@"right"]) {   return 6;  } } return 0;}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{ CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath]; cell.label.text = [NSString stringWithFormat:@"%ld-%ld",indexPath.section,indexPath.row]; return cell;}- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{ if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {  CollectionSectionView *sectionView = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:sectionIdentifier forIndexPath:indexPath];  sectionView.backgroundColor = [UIColor lightGrayColor];  sectionView.leftStr = @"家具";  sectionView.rightStr = @"家电";  [sectionView customBtnHandelAction:^(NSString *leftOrRight) {   self.clickIndexPath = indexPath;   self.leftOrRight = leftOrRight;   [collectionView reloadData];  }];  return sectionView; } return nil;}- (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated.}

#import <UIKit/UIKit.h>typedef void(^BtnHandleAction)(NSString *leftOrRight);@interface CollectionSectionView : UICollectionReusableView@property (nonatomic,copy)NSString *leftStr;@property (nonatomic,copy)NSString *rightStr;- (void)customBtnHandelAction:(BtnHandleAction)action;@end

#import "CollectionSectionView.h"@interface CollectionSectionView ()@property (nonatomic,strong)UIButton *leftBtn;@property (nonatomic,strong)UIButton *rightBtn;@property (nonatomic,copy)BtnHandleAction btnHandelAction;@end@implementation CollectionSectionView- (instancetype)initWithFrame:(CGRect)frame{ self = [super initWithFrame:frame]; if (self) {  [self setup]; } return self;}- (UIButton *)leftBtn{ if (!_leftBtn) {  self.leftBtn = [UIButton buttonWithType:(UIButtonTypeCustom)];  _leftBtn.tag = 2000;  _leftBtn.frame = CGRectMake(1, 1, self.frame.size.width / 2 - 2, self.frame.size.height - 2);  _leftBtn.backgroundColor = [UIColor whiteColor];  [_leftBtn addTarget:self action:@selector(btnAction:) forControlEvents:(UIControlEventTouchUpInside)]; } return _leftBtn;}- (UIButton *)rightBtn{ if (!_rightBtn) {  self.rightBtn = [UIButton buttonWithType:(UIButtonTypeCustom)];  _rightBtn.tag = 2001;  _rightBtn.frame = CGRectMake(self.frame.size.width / 2 + 1, 1, self.frame.size.width / 2 - 2, self.frame.size.height - 2);  _rightBtn.backgroundColor = [UIColor whiteColor];  [_rightBtn addTarget:self action:@selector(btnAction:) forControlEvents:(UIControlEventTouchUpInside)]; } return _rightBtn;}- (void)btnAction:(UIButton *)sender{ NSInteger tag = sender.tag; if (tag == 2000) {  self.btnHandelAction(@"left"); } if (tag == 2001) {  self.btnHandelAction(@"right"); }}- (void)customBtnHandelAction:(BtnHandleAction)action{ self.btnHandelAction = action;}- (void)setup{ [self addSubview:self.leftBtn]; [self addSubview:self.rightBtn];}- (void)setLeftStr:(NSString *)leftStr{ [self.leftBtn setTitle:leftStr forState:(UIControlStateNormal)]; [self.leftBtn setTitleColor:[UIColor blackColor] forState:(UIControlStateNormal)];}- (void)setRightStr:(NSString *)rightStr{ [self.rightBtn setTitle:rightStr forState:(UIControlStateNormal)]; [self.rightBtn setTitleColor:[UIColor blackColor] forState:(UIControlStateNormal)];}@end