iOS如何用100行代码实现简单的抽屉效果

#import <UIKit/UIKit.h>@interface MainViewController : UIViewController+ (instancetype)mainViewControllerWithLeftViewController:(UIViewController *)leftViewController withMainPageViewController:(UIViewController *)mainPageViewController;@end

#import "MainViewController.h"#define KWidth self.view.frame.size.width#define KHeight self.view.frame.size.height@interface MainViewController ()@property (nonatomic,strong)UIViewController *leftVC;@property (nonatomic,strong)UIViewController *centerVC;@property (nonatomic,assign)BOOL isSlider;@property (nonatomic,strong)UIView *corverView;@end@implementation MainViewController+ (instancetype)mainViewControllerWithLeftViewController:(UIViewController *)leftViewController withMainPageViewController:(UIViewController *)mainPageViewController{  MainViewController *mainVC = [[MainViewController alloc] init];  mainVC.leftVC = leftViewController;  mainVC.centerVC = mainPageViewController;  return mainVC;}- (void)viewDidLoad{  [super viewDidLoad];  self.isSlider = NO;  self.view.backgroundColor = [UIColor whiteColor];  [self addChildViewController:self.leftVC];  [self.view addSubview:self.leftVC.view];  [self addChildViewController:self.centerVC];  [self.view addSubview:self.centerVC.view];  // 给左视图和主视图添加手势  [self addGestureForView];}// 给主视图添加遮盖- (void)addCorverView{  if (self.corverView) {    [self.corverView removeFromSuperview];    self.corverView = nil;  }  self.corverView = [[UIView alloc] initWithFrame:self.centerVC.view.bounds];  _corverView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.0];  [self.centerVC.view addSubview:self.corverView];}// 移除主视图遮盖- (void)removeCoverView{  if (self.corverView) {    [self.corverView removeFromSuperview];    self.corverView = nil;  }}// 给左视图和主视图添加手势- (void)addGestureForView{  UISwipeGestureRecognizer *rightGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeRightAction:)];  rightGesture.direction = UISwipeGestureRecognizerDirectionRight;  [self.centerVC.view addGestureRecognizer:rightGesture];  UISwipeGestureRecognizer *leftGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeLeftAction:)];  leftGesture.direction = UISwipeGestureRecognizerDirectionLeft;  [self.centerVC.view addGestureRecognizer:leftGesture];  UISwipeGestureRecognizer *leftVCLeftSwipeGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(leftVCLeftSwipeAction:)];  leftVCLeftSwipeGesture.direction = UISwipeGestureRecognizerDirectionLeft;  [self.leftVC.view addGestureRecognizer:leftVCLeftSwipeGesture];}- (void)swipeRightAction:(id)sender{  [self moveView:self.centerVC.view scale:0.8 panValue:KWidth];  self.isSlider = YES;  [self addCorverView];}- (void)swipeLeftAction:(id)sender{  [self moveView:self.centerVC.view scale:1 panValue:KWidth / 2];  self.isSlider = NO;  [self removeCoverView];}- (void)leftVCLeftSwipeAction:(id)sender{  [self moveView:self.centerVC.view scale:1 panValue:KWidth / 2];  self.isSlider = NO;  [self removeCoverView];}// 平移和缩放一个视图- (void)moveView:(UIView *)view scale:(CGFloat)scale panValue:(CGFloat)value{  [UIView beginAnimations:nil context:nil];  view.transform = CGAffineTransformScale(CGAffineTransformIdentity,scale,scale);  view.center = CGPointMake(value, view.center.y);  [UIView commitAnimations];}@end