我正在尝试实现模态呈现效果,其中所呈现的视图仅部分覆盖父视图,如下图所示.
我知道我可以通过使用UIPresentationController实现自定义转换来实现这一点.我不想重新发明,所以在我开始发展之前,我想问一下.
在API中是否有这种转型的支持？
我研究了所有可用的Modal Presentation Styles,在我看来,我不想支持我想要的转换,唯一的方法就是编写它.
解决方法
我遇到了同样的问题.我也去了模式演示风格的路线,并不断击中墙壁(具体让它在iPhone而不是iPad上工作).
经过一些挖掘,我能够得到它的工作.这是我如何做到的：
要开始,我们需要一个视图控制器,我们将呈现(模态的)将其视图的背景颜色设置为透明,并将导航控制器视图的框架设置为一些偏移.
ModalViewController.h
@import UIKit; @class ModalViewController; @protocol ModalViewControllerDelegate <NSObject> - (void)modalViewControllerDidCancel:(ModalViewController *)modalViewController; @end @interface ModalViewController : UIViewController @property (weak,nonatomic) id<ModalViewControllerDelegate> delegate; - (instancetype)initWithRootViewController:(UIViewController *)rootViewController; @end
ModalViewController.m
static const CGFloat kTopOffset = 50.0f;
@implementation ModalViewController {
UINavigationController *_navController;
}
- (instancetype)initWithRootViewController:(UIViewController *)rootViewController
{
self = [super initWithNibName:nil bundle:nil];
if (self) {
rootViewController.navigationItem.leftBarButtonItem = [self cancelButton];
_navController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
self.view.backgroundColor = [UIColor clearColor];
[self.view addSubview:_navController.view];
// this is important (prevents black overlay)
self.modalPresentationStyle = UIModalPresentationOverFullScreen;
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
CGRect bounds = self.view.bounds;
_navController.view.frame = CGRectMake(0,kTopOffset,CGRectGetWidth(bounds),CGRectGetHeight(bounds) - kTopOffset);
}
- (UIBarButtonItem *)cancelButton
{
return [[UIBarButtonItem alloc] initWithTitle:@"Cancel" style:UIBarButtonItemStylePlain target:self action:@selector(cancelButtonClicked:)];
}
- (void)cancelButtonClicked:(id)sender
{
[_delegate modalViewControllerDidCancel:self];
}
@end
接下来,我们需要设置演示控制器来运行以下动画：
>缩小自己
淡出一点点
>使用presentViewController呈现模态视图控制器：动画：完成
这就是我所做的
PresentingViewController.m
static const CGFloat kTransitionScale = 0.9f;
static const CGFloat kTransitionAlpha = 0.6f;
static const NSTimeInterval kTransitionDuration = 0.5;
@interface PresentingViewController <ModalViewControllerDelegate>
@end
@implementation PresentingViewController
...
...
- (void)showModalViewController
{
self.navigationController.view.layer.shouldRasterize = YES;
self.navigationController.view.layer.rasterizationScale = [UIScreen mainScreen].scale;
UIViewController *controller = // init some view controller
ModalViewController *container = [[ModalViewController alloc] initWithRootViewController:controller];
container.delegate = self;
__weak UIViewController *weakSelf = self;
[UIView animateWithDuration:kTransitionDuration animations:^{
weakSelf.navigationController.view.transform = CGAffineTransformMakeScale(kTransitionScale,kTransitionScale);
weakSelf.navigationController.view.alpha = kTransitionAlpha;
[weakSelf presentViewController:container animated:YES completion:nil];
} completion:^(BOOL finished) {
weakSelf.navigationController.view.layer.shouldRasterize = NO;
}];
}
#pragma mark - ModalViewControllerDelegate
- (void)modalViewControllerDidCancel:(ModalViewController *)modalViewController
{
__weak UIViewController *weakSelf = self;
[UIView animateWithDuration:kTransitionDuration animations:^{
weakSelf.navigationController.view.alpha = 1;
weakSelf.navigationController.view.transform = CGAffineTransformIdentity;
[weakSelf dismissViewControllerAnimated:YES completion:nil];
}];
}
@end
