手写CollectionView并调整布局

创建

 if (!_colcView)         int colcViewSideLength = self.view.frame.size.width - cellGap;        UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc]init];        _colcView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, colcViewSideLength, colcViewSideLength) collectionViewLayout:flowLayout];        _colcView.showsHorizontalScrollIndicator = NO;        _colcView.showsVerticalScrollIndicator = NO;        _colcView.delegate = self;        _colcView.dataSource = self;        _colcView.center = self.view.center;        _colcView.backgroundColor = [UIColor clearColor];        [_colcView registerClass:[EPLGuestureColcViewCell class] forCellWithReuseIdentifier:CellID];        [self.view addSubview:_colcView];    }

实现协议

#pragma mark - UICollectionViewDataSource- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return _arrBtnImg.count;}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    EPLGuestureColcViewCell *colcCell = [collectionView dequeueReusableCellWithReuseIdentifier:CellID forIndexPath:indexPath];    if (!colcCell) {        colcCell = [[EPLGuestureColcViewCell alloc]initWithFrame:CGRectZero];    }    [colcCell sizeToFit];    return colcCell;}-(void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath{    EPLGuestureColcViewCell *cell0 = (EPLGuestureColcViewCell*)cell;    cell0.imgView.image = [UIImage imageNamed:_arrBtnImg[indexPath.item]];    NSNumber *numValue;    if (_arrBtnValues.count) {        numValue = _arrBtnValues[indexPath.item];    }else{        numValue = [NSNumber numberWithInt:-1];    }    switch (numValue.intValue) {        case -1:            cell0.labTitle.text = NSLocalizedString(@"GUESTURE_BUTTON_CHOOSE_SHOORTKEY", nil);            break;        case 0:            cell0.labTitle.text = NSLocalizedString(@"GUESTURESETTING_ROW_PHONE", nil);            break;        case 1:            cell0.labTitle.text = NSLocalizedString(@"GUESTURESETTING_ROW_SMS", nil);            break;        case 2:            cell0.labTitle.text = NSLocalizedString(@"GUESTURESETTING_ROW_RECORDER", nil);            break;        case 3:            cell0.labTitle.text = NSLocalizedString(@"GUESTURESETTING_ROW_CAMERA", nil);            break;        default:            break;    }}#pragma mark -- UICollectionViewDelegate- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{    [collectionView deselectItemAtIndexPath:indexPath animated:YES];    NSNumber *shortcutKey;    if (_arrBtnValues.count) {        shortcutKey = _arrBtnValues[indexPath.item];    }else{        shortcutKey = [NSNumber numberWithInt:-1];    }    EPLGuestureSettingController *settingController = [[EPLGuestureSettingController alloc]initWithStyle:UITableViewStyleGrouped];    settingController.selectedIndex = shortcutKey.integerValue;    settingController.currentShortcutKeyName = _arrBtnKeys[indexPath.item];    settingController.shortcutKeyUpdated = ^(NSNumber *selectedIndex){        [_arrBtnValues replaceObjectAtIndex:indexPath.item withObject:selectedIndex];        NSDictionary *dicGuestureShortcutKeysValue = [NSDictionary dictionaryWithObjects:_arrBtnValues forKeys:_arrBtnKeys];        [EPLDataOperateKit saveGuestureShortcutKeysValue:dicGuestureShortcutKeysValue];        [_colcView reloadData];    };    [self.navigationController pushViewController:settingController animated:YES];}#pragma mark -- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{    int cellEdgeLength = (collectionView.frame.size.width-2*indicatorInsets-cellGap)/2;    return CGSizeMake(cellEdgeLength, cellEdgeLength);}- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{    if (isEliteDevice) {        return UIEdgeInsetsMake(indicatorInsets, indicatorInsets, indicatorInsets, indicatorInsets);    }else{        int cellEdgeLength = (collectionView.frame.size.width-2*indicatorInsets-cellGap)/2;        int indicatorInsetsForSigleItem = indicatorInsets + cellGap/2 + cellEdgeLength;        return UIEdgeInsetsMake(indicatorInsetsForSigleItem/2, indicatorInsetsForSigleItem/2, indicatorInsetsForSigleItem/2, indicatorInsetsForSigleItem/2);    }}- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{    return cellGap;}- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section{    return cellGap;}