#import "ViewController.h"
#import "RedViewController.h"
#import "CustomPresentationController.h"

@interface ViewController () <UIViewControllerTransitioningDelegate>


@end





@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
 
    self.view.backgroundColor = [UIColor whiteColor];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    RedViewController *vc = [[RedViewController alloc] init];
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:vc];
    nav.modalPresentationStyle = UIModalPresentationCustom;
    nav.transitioningDelegate = self;
    [self presentViewController:nav animated:YES completion:nil];
}

#pragma mark - UIViewControllerTransitioningDelegate
- (UIPresentationController *)presentationControllerForPresentedViewController:(UIViewController *)presented
                                                      presentingViewController:(UIViewController *)presenting sourceViewController:(UIViewController *)source
{
    CustomPresentationController *vc = [[CustomPresentationController alloc] initWithPresentedViewController:presented
                                                                                    presentingViewController:presenting];
    return vc;
}


@end

@implementation RedViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor redColor];
    self.view.layer.cornerRadius = 16;

    UIBarButtonItem *doneItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone
                                                                              target:self
                                                                              action:@selector(doneItemAction:)];
    self.navigationItem.leftBarButtonItem = doneItem;
}

- (void)doneItemAction:(id)sender
{
    [self dismissViewControllerAnimated:YES completion:nil];
}

@implementation CustomPresentationController

- (CGRect)frameOfPresentedViewInContainerView
{
    return CGRectMake(0, 200, self.containerView.width, self.containerView.height);
}

@end

Demo: https://gitee.com/lazyoung/modal-view-demo.git

参考文章自定义拖拽：https://kittenyang.com/uipresentation/