创建首页下拉菜单，本节先完成下拉菜单界面的创建，下节再微调其位置。

DJDropdownMenu.h

#import 
     
      @interface DJDropdownMenu : UIView/** 构造方法 */+ (instancetype)menu;/** 显示 */- (void)show;/** 消失 */- (void)dismiss;@property (nonatomic,weak) UIView *contentView;@property (nonatomic,strong) UIViewController *contentController;@end
     

 

DJDropdownMenu.m

#import "DJDropdownMenu.h"@interface DJDropdownMenu()/** 灰色背景 */@property (nonatomic,weak) UIImageView *containerView;@end@implementation DJDropdownMenu- (UIImageView *)containerView {    if (!_containerView) {        UIImageView *imageView = [[UIImageView alloc] init];        imageView.width = 217;        imageView.height = 217;        imageView.image = [UIImage imageNamed:@"popover_background"];        [self addSubview:imageView];        _containerView = imageView;    }    return _containerView;}- (void)setContentView:(UIView *)contentView {    _contentView = contentView;        // 1. 设置contentView位置    contentView.x = 10;    contentView.y = 15;        // 2. 设置contentView宽度(防止宽度过长导致图片拉伸变形)    contentView.width = self.containerView.width - 2* contentView.x;            // 3. 设置containerView高度(随contentView高度的变化而变化)    self.containerView.height = CGRectGetMaxY(contentView.frame)+12;        // 4.添加contentView至containerView;    [self.containerView addSubview:contentView];        }- (void)setContentController:(UIViewController *)contentController {    _contentController = contentController;    [self setContentView:contentController.view];}- (instancetype)initWithFrame:(CGRect)frame {    if (self = [super initWithFrame:frame]) {        // 1.设置背景颜色透明        self.backgroundColor = [UIColor clearColor];        // 2.设置containerView可以与用户交互        self.containerView.userInteractionEnabled = YES;    }    return self;}+ (instancetype)menu {    return [[self alloc] init];}/** show即是将当前View添加到顶层窗口上 */- (void)show {    // 1. 获取顶层窗口    UIWindow *window = [[UIApplication sharedApplication].windows lastObject];        // 2. 设置当前View大小    self.frame = window.bounds;        // 3. 添加当前View到顶层窗口    [window addSubview:self];    }/** dismiss即是将当前View从顶层窗口移除 */- (void)dismiss {    [self removeFromSuperview];}@end

 

最终效果：