iOS 下拉列表控件-白红宇

自己封装了一个简单的下拉列表控件，会根据控件所在屏幕位置自动计算列表是该向上还是向下弹出，调用简单。

效果图

调用方式

// 数据源    EBDropdownListItem *item1 = [[EBDropdownListItem alloc] initWithItem:@"1" itemName:@"item1"];    EBDropdownListItem *item2 = [[EBDropdownListItem alloc] initWithItem:@"2" itemName:@"item2"];    EBDropdownListItem *item3 = [[EBDropdownListItem alloc] initWithItem:@"3" itemName:@"item3"];    EBDropdownListItem *item4 = [[EBDropdownListItem alloc] initWithItem:@"4" itemName:@"item4"];    EBDropdownListView *dropdownListView = [[EBDropdownListView alloc] initWithDataSource:@[item1, item2, item3, item4]];    dropdownListView.frame = CGRectMake(20, 100, 130, 30);    // 设置当前显示第几项，默认为0    dropdownListView.selectedIndex = 2;    // 字体默认14    //dropdownListView.font = [UIFont systemFontOfSize:14];    // 默认颜色blackColor    //dropdownListView.textColor = [UIColor blackColor];    [dropdownListView setViewBorder:0.5 borderColor:[UIColor grayColor] cornerRadius:2];    [self.view addSubview:dropdownListView];        [dropdownListView setDropdownListViewSelectedBlock:^(EBDropdownListView *dropdownListView) {        NSString *msgString = [NSString stringWithFormat:                               @"selected name:%@  id:%@  index:%ld"                               , dropdownListView.selectedItem.itemName                               , dropdownListView.selectedItem.itemId                               , dropdownListView.selectedIndex];                msgLabel.text = msgString;            }];复制代码

代码结构

定义一个Model类，用于存放下拉列表的数据

@interface EBDropdownListItem : NSObject@property (nonatomic, copy, readonly) NSString *itemId;@property (nonatomic, copy, readonly) NSString *itemName;- (instancetype)initWithItem:(NSString*)itemId itemName:(NSString*)itemName NS_DESIGNATED_INITIALIZER;@end复制代码

#import "EBDropdownListView.h"@implementation EBDropdownListItem- (instancetype)initWithItem:(NSString*)itemId itemName:(NSString*)itemName {    self = [super init];    if (self) {        _itemId = itemId;        _itemName = itemName;    }    return self;}- (instancetype)init {    return [self initWithItem:nil itemName:nil];}@end复制代码

创建EBDropdownListView继承自UIView

typedef void (^EBDropdownListViewSelectedBlock)(EBDropdownListView *dropdownListView);@interface EBDropdownListView : UIView// 字体颜色，默认 blackColor@property (nonatomic, strong) UIColor *textColor;// 字体默认14@property (nonatomic, strong) UIFont *font;// 数据源@property (nonatomic, strong) NSArray *dataSource;// 默认选中第一个@property (nonatomic, assign) NSUInteger selectedIndex;// 当前选中的DropdownListItem@property (nonatomic, strong, readonly) EBDropdownListItem *selectedItem;- (instancetype)initWithDataSource:(NSArray*)dataSource;- (void)setViewBorder:(CGFloat)width borderColor:(UIColor*)borderColor cornerRadius:(CGFloat)cornerRadius;- (void)setDropdownListViewSelectedBlock:(EBDropdownListViewSelectedBlock)block;复制代码

代码都挺简单的，可以设置字体大小、颜色、数据源、选中项。默认是没有边框的，可以通过setViewBorder 方法去设置。EBDropdownListViewSelectedBlock选中下拉列表项时的回调。

备注:

该控件两点比较重要的地方: 1.点击控件弹出的下拉框是放在UIWindows上的，这样就不会被父视图或其他视图所遮挡。 2.下拉框弹出的起始位置是根据控件所在屏幕上的位置去计算的。