最近自由时间有点多，就开始撸控件。这个是我们常用的一个下拉分类控件，看了很多别人写的，都是用TableView或者CollectionView整合在一起的感觉自定义性没有那么强，所以就尝试用把TableView和CollectionView替换成UIViewController。其他废话不多说了。

1、 接口文件

#import <UIKit/UIKit.h>UIKIT_EXTERN NSString *lzDropViewNotification;NS_ASSUME_NONNULL_BEGIN@class LZDropView;
@protocol LZDropViewDataSource <NSObject>@required/** Height corresponding to controller display */
- (NSArray<NSNumber *> *)setupCategoryControllerHeightInDropView:(LZDropView *)dropView;
/** Title corresponding controller array */
- (NSArray<UIViewController *> *)setupCategoryControllerInDropView:(LZDropView *)dropView;
/** Default display of Title Array */
- (NSArray<NSString *> *)setupCategoryTitleNameInDropView:(LZDropView *)dropView;@end@protocol LZDropViewDelegate <NSObject>/** Click the column and select the information. */
- (void)dropView:(LZDropView *)dropView didSelectAtColumn:(NSInteger)column info:(NSString *)info;@end@interface LZDropView : UIView
/** Simple page configuration */
@property (nonatomic, weak) id <LZDropViewDataSource> dataSorce;
/** Click proxy event<##> */
@property (nonatomic, weak) id <LZDropViewDelegate> delegate;@endNS_ASSUME_NONNULL_END
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2、 实现文件

#import "LZDropView.h"NSString *lzDropViewNotification = @"nitification";@interface LZDropView ()@property (nonatomic, strong) NSArray<UIViewController *> *controllerArray;
@property (nonatomic, strong) NSArray<NSString *> *titleArray;
@property (nonatomic, strong) UIButton *containerView;
@property (nonatomic, strong) NSArray<NSNumber *> *controllerHeightArray;
@property (nonatomic, strong) NSMutableArray<UIButton *> *buttonArray;@end@implementation LZDropView#pragma mark - Release memory- (void)dealloc {[[NSNotificationCenter defaultCenter] removeObserver:self];
}#pragma mark - Initialization- (instancetype)init {self = [super init];if (self) {[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(notificationAction:) name:lzDropViewNotification object:nil];}return self;
}#pragma mark - Draw the page- (void)setupTitleButton:(NSArray<NSString *> *)array {CGFloat width = UIScreen.mainScreen.bounds.size.width / array.count;self.buttonArray = [NSMutableArray array];for (NSString *name in array) {NSInteger index = [array indexOfObject:name];UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];button.titleLabel.font = [UIFont systemFontOfSize:15];[button setTitle:[NSString stringWithFormat:@"%@ ▼", name] forState:UIControlStateNormal];[button setTitle:[NSString stringWithFormat:@"%@ ▲", name] forState:UIControlStateSelected];[button setTitleColor:UIColor.grayColor forState:UIControlStateNormal];[button setTitleColor:UIColor.orangeColor forState:UIControlStateSelected];button.frame = CGRectMake(width * index, 0, width, 45);button.tag = index + 1000;[button addTarget:self action:@selector(buttonTouched:) forControlEvents:UIControlEventTouchUpInside];[self addSubview:button];[self.buttonArray addObject:button];}
}#pragma mark - Button click event- (void)buttonTouched:(UIButton *)sender {if (sender.selected) {[self closeControllerView];} else {[self openControllerViewWithButton:sender];}
}- (void)backButtonTouched:(UIButton *)sender {[self closeControllerView];
}#pragma mark - Notification event- (void)notificationAction:(NSNotification *)notification {    if (![self.controllerArray containsObject:notification.object]) {return;}NSInteger index = [self.controllerArray indexOfObject:notification.object];UIButton *button = self.buttonArray[index];[button setTitle:[NSString stringWithFormat:@"%@ ▼", notification.userInfo.allValues.firstObject] forState:UIControlStateNormal];if (self.delegate && [self.delegate respondsToSelector:@selector(dropView:didSelectAtColumn:info:)]) {[self.delegate dropView:self didSelectAtColumn:index info:notification.userInfo.allValues.firstObject];}[self closeControllerView];
}#pragma mark - Close all controllers.- (void)closeControllerView {[UIView animateWithDuration:0.8 animations:^{self.containerView.alpha = 0;self.containerView.frame = CGRectMake(0, CGRectGetMaxY(self.frame), UIScreen.mainScreen.bounds.size.width, 0);} completion:^(BOOL finished) {[self.containerView removeFromSuperview];}];for (UIButton *button in self.buttonArray) {button.selected = false;}
}#pragma mark - Open the corresponding controller.- (void)openControllerViewWithButton:(UIButton *)sender {for (UIButton *button in self.buttonArray) {button.selected = false;}self.containerView.alpha = 1;for (UIView *view in self.containerView.subviews) {[view removeFromSuperview];}UIViewController *vc = self.controllerArray[sender.tag - 1000];double vcHeight = [self.controllerHeightArray[sender.tag - 1000] doubleValue];self.containerView.frame = CGRectMake(0, CGRectGetMaxY(self.frame), self.frame.size.width, 0);vc.view.frame = CGRectMake(0, 0, UIScreen.mainScreen.bounds.size.width, 0);[self.superview addSubview:self.containerView];[self.containerView addSubview:vc.view];[UIView animateWithDuration:0.6 animations:^{self.containerView.frame = CGRectMake(0, CGRectGetMaxY(self.frame), self.frame.size.width, UIScreen.mainScreen.bounds.size.height);vc.view.frame = CGRectMake(0, 0, UIScreen.mainScreen.bounds.size.width, vcHeight);} completion:^(BOOL finished) {}];sender.selected = true;
}#pragma mark - Getter- (UIView *)containerView {if (!_containerView) {_containerView = [[UIButton alloc] init];_containerView.backgroundColor = [UIColor colorWithWhite:0 alpha:0.1];[_containerView addTarget:self action:@selector(backButtonTouched:) forControlEvents:UIControlEventTouchUpInside];}return _containerView;
}#pragma mark - Setter- (void)setDataSorce:(id<LZDropViewDataSource>)dataSorce {_dataSorce = dataSorce;if (self.dataSorce && [self.dataSorce respondsToSelector:@selector(setupCategoryControllerInDropView:)]){self.controllerArray = [self.dataSorce setupCategoryControllerInDropView:self];}if (self.dataSorce && [self.dataSorce respondsToSelector:@selector(setupCategoryTitleNameInDropView:)]){self.titleArray = [self.dataSorce setupCategoryTitleNameInDropView:self];[self setupTitleButton:self.titleArray];}if (self.dataSorce && [self.dataSorce respondsToSelector:@selector(setupCategoryControllerHeightInDropView:)]) {self.controllerHeightArray = [self.dataSorce setupCategoryControllerHeightInDropView:self];}if (self.controllerArray.count != self.titleArray.count ||self.controllerArray.count != self.controllerHeightArray.count) {@throw [NSException exceptionWithName:NSStringFromClass([self class]) reason:@"The number of corresponding arrays is inconsistent." userInfo:nil];}
}@end
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使用方式

1.遵循协议

<LZDropViewDataSource, LZDropViewDelegate>
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2.初始化

LZDropView *view     = [[LZDropView alloc] init];view.dataSorce       = self;view.delegate        = self;view.backgroundColor = UIColor.whiteColor;view.frame           = CGRectMake(0, 100, UIScreen.mainScreen.bounds.size.width, 45);[self.view addSubview:view];
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1. 实现代理和数据源

#pragma mark - LZDropViewDataSource- (NSArray<UIViewController *> *)setupCategoryControllerInDropView:(LZDropView *)dropView {return @[[[TableViewController alloc] init],[[TableViewController alloc] init],[[TableViewController alloc] init],[[TableViewController alloc] init]];
}- (NSArray<NSString *> *)setupCategoryTitleNameInDropView:(LZDropView *)dropView {return @[@"全部",@"附近",@"只能排序",@"筛选"];
}- (NSArray<NSNumber *> *)setupCategoryControllerHeightInDropView:(LZDropView *)dropView {return @[[NSNumber numberWithFloat:300],[NSNumber numberWithFloat:400],[NSNumber numberWithFloat:410],[NSNumber numberWithFloat:420]];
}#pragma mark - LZDropViewDelegate- (void)dropView:(LZDropView *)dropView didSelectAtColumn:(NSInteger)column info:(NSString *)info {NSLog(@"%ld---%@", column, info);
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1. 点击controller中的数据显示在按钮的标题中，这因为跨界面显示，我暂时没有想到好的办法，所以使用强大的通知传值。
2. 记录选中状态，应该是控制器里面的操作，这里就没有实现

[[NSNotificationCenter defaultCenter] postNotificationName:lzDropViewNotification object:self userInfo:@{@"key":[NSString stringWithFormat:@"第%ldcell", indexPath.row]}];
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如果有什么不好如果建议的地方，请批评指正！