我正在创建一个使用 UINavigationController 来呈现下一个视图控制器的应用程序。
在 iOS5 中，有一种新方法来呈现 UIViewControllers：
presentViewController:animated:completion:
现在我想知道为什么UINavigationController没有完成处理程序？
只有
pushViewController:animated:
我能否像新的 presentViewController:animated:completion: 一样创建自己的完成处理程序？
参见 par的答案，这是另一种更为实用且更新的解决方案
UINavigationController 的动画是通过 CoreAnimation 实现的，因此将代码封装在 CATransaction 中并设置完成回调函数是有意义的。
Swift:
对于 Swift，我建议创建一个扩展(extension)，如下所示
extension UINavigationController {
public func pushViewController(viewController: UIViewController,
animated: Bool,
completion: @escaping (() -> Void)?) {
CATransaction.begin()
CATransaction.setCompletionBlock(completion)
pushViewController(viewController, animated: animated)
CATransaction.commit()
}
}
使用方法：
navigationController?.pushViewController(vc, animated: true) {
// Animation done
}
Objective-C
头文件：
#import <UIKit/UIKit.h>
@interface UINavigationController (CompletionHandler)
- (void)completionhandler_pushViewController:(UIViewController *)viewController
animated:(BOOL)animated
completion:(void (^)(void))completion;
@end
实现:
#import "UINavigationController+CompletionHandler.h"
#import <QuartzCore/QuartzCore.h>
@implementation UINavigationController (CompletionHandler)
- (void)completionhandler_pushViewController:(UIViewController *)viewController
animated:(BOOL)animated
completion:(void (^)(void))completion
{
[CATransaction begin];
[CATransaction setCompletionBlock:completion];
[self pushViewController:viewController animated:animated];
[CATransaction commit];
}
@end
pushViewController:animated: 或 popViewController:animated 时，viewDidLoad 和 viewDidAppear 的调用会在后续的运行循环周期中发生。因此，我的印象是，即使这些方法确实调用了动画，它们也不会成为代码示例中提供的事务的一部分。这是你担心的吗？因为这个解决方案非常简单而出色。 - LeffelManiadidShowViewController中可以保证所涉及的视图控制器已显示。虽然这个解决方案非常简单，但我会质疑它的“面向未来性”。特别是考虑到随着iOS7/8引入的视图生命周期回调的变化。 - SamiOS 7+ Swift
Swift 4:
// 2018.10.30 par:
// I've updated this answer with an asynchronous dispatch to the main queue
// when we're called without animation. This really should have been in the
// previous solutions I gave but I forgot to add it.
extension UINavigationController {
public func pushViewController(
_ viewController: UIViewController,
animated: Bool,
completion: @escaping () -> Void)
{
pushViewController(viewController, animated: animated)
guard animated, let coordinator = transitionCoordinator else {
DispatchQueue.main.async { completion() }
return
}
coordinator.animate(alongsideTransition: nil) { _ in completion() }
}
func popViewController(
animated: Bool,
completion: @escaping () -> Void)
{
popViewController(animated: animated)
guard animated, let coordinator = transitionCoordinator else {
DispatchQueue.main.async { completion() }
return
}
coordinator.animate(alongsideTransition: nil) { _ in completion() }
}
}
编辑：我已经添加了我的原始答案的Swift 3版本。在这个版本中，我删除了Swift 2版本中显示的示例共同动画，因为它似乎使很多人感到困惑。
Swift 3：
import UIKit
// Swift 3 version, no co-animation (alongsideTransition parameter is nil)
extension UINavigationController {
public func pushViewController(
_ viewController: UIViewController,
animated: Bool,
completion: @escaping (Void) -> Void)
{
pushViewController(viewController, animated: animated)
guard animated, let coordinator = transitionCoordinator else {
completion()
return
}
coordinator.animate(alongsideTransition: nil) { _ in completion() }
}
}
Swift 2:
import UIKit
// Swift 2 Version, shows example co-animation (status bar update)
extension UINavigationController {
public func pushViewController(
viewController: UIViewController,
animated: Bool,
completion: Void -> Void)
{
pushViewController(viewController, animated: animated)
guard animated, let coordinator = transitionCoordinator() else {
completion()
return
}
coordinator.animateAlongsideTransition(
// pass nil here or do something animated if you'd like, e.g.:
{ context in
viewController.setNeedsStatusBarAppearanceUpdate()
},
completion: { context in
completion()
}
)
}
}
nil作为动画块似乎可以正常工作。 - Mike Spraguenil也是完全有效的。 - partransitionCoordinator 为 nil 时调用 completion 吗？ - Aurelien PortetransitionCoordinator，那么很可能是在导航控制器的生命周期中过早地调用了此函数。请至少等到viewWillAppear()被调用后再尝试使用动画推送视图控制器。 - par基于par的答案（在iOS9下是唯一有效的），但更简单，并且去掉了else语句（否则可能导致不会调用完成）：
extension UINavigationController {
func pushViewController(_ viewController: UIViewController, animated: Bool, completion: @escaping () -> Void) {
pushViewController(viewController, animated: animated)
if animated, let coordinator = transitionCoordinator {
coordinator.animate(alongsideTransition: nil) { _ in
completion()
}
} else {
completion()
}
}
func popViewController(animated: Bool, completion: @escaping () -> Void) {
popViewController(animated: animated)
if animated, let coordinator = transitionCoordinator {
coordinator.animate(alongsideTransition: nil) { _ in
completion()
}
} else {
completion()
}
}
}
目前UINavigationController不支持此功能。但是可以使用UINavigationControllerDelegate。
一种简单的方法是通过对UINavigationController进行子类化并添加完成块属性来实现：
@interface PbNavigationController : UINavigationController <UINavigationControllerDelegate>
@property (nonatomic,copy) dispatch_block_t completionBlock;
@end
@implementation PbNavigationController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
self.delegate = self;
}
return self;
}
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
NSLog(@"didShowViewController:%@", viewController);
if (self.completionBlock) {
self.completionBlock();
self.completionBlock = nil;
}
}
@end
在推送新的视图控制器之前，您需要设置完成块：
UIViewController *vc = ...;
((PbNavigationController *)self.navigationController).completionBlock = ^ {
NSLog(@"COMPLETED");
};
[self.navigationController pushViewController:vc animated:YES];
这个新的子类可以在Interface Builder中分配，也可以像这样通过编程来使用：
PbNavigationController *nc = [[PbNavigationController alloc]initWithRootViewController:yourRootViewController];
pushViewController:animated:completion:，将使其成为一种优雅的解决方案。 - Hyperbole这里是带有 Pop 的 Swift 4 版本。
extension UINavigationController {
public func pushViewController(viewController: UIViewController,
animated: Bool,
completion: (() -> Void)?) {
CATransaction.begin()
CATransaction.setCompletionBlock(completion)
pushViewController(viewController, animated: animated)
CATransaction.commit()
}
public func popViewController(animated: Bool,
completion: (() -> Void)?) {
CATransaction.begin()
CATransaction.setCompletionBlock(completion)
popViewController(animated: animated)
CATransaction.commit()
}
}
万一有其他人需要这个，我分享一下。
扩展@Klaas的答案（并由于这个问题），我直接向推送方法添加了完成块：
@interface PbNavigationController : UINavigationController <UINavigationControllerDelegate>
@property (nonatomic,copy) dispatch_block_t completionBlock;
@property (nonatomic,strong) UIViewController * pushedVC;
@end
@implementation PbNavigationController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
self.delegate = self;
}
return self;
}
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
NSLog(@"didShowViewController:%@", viewController);
if (self.completionBlock && self.pushedVC == viewController) {
self.completionBlock();
}
self.completionBlock = nil;
self.pushedVC = nil;
}
-(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
if (self.pushedVC != viewController) {
self.pushedVC = nil;
self.completionBlock = nil;
}
}
-(void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated completion:(dispatch_block_t)completion {
self.pushedVC = viewController;
self.completionBlock = completion;
[self pushViewController:viewController animated:animated];
}
@end
以下是使用方法：
UIViewController *vc = ...;
[(PbNavigationController *)self.navigationController pushViewController:vc animated:YES completion:^ {
NSLog(@"COMPLETED");
}];
UIViewControllerTransitionCoordinator添加推送完成块：UINavigationController *nav = self.navigationController;
[nav pushViewController:vc animated:YES];
id<UIViewControllerTransitionCoordinator> coordinator = vc.transitionCoordinator;
[coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> _Nonnull context) {
} completion:^(id<UIViewControllerTransitionCoordinatorContext> _Nonnull context) {
NSLog(@"push completed");
}];
Swift 2.0
extension UINavigationController : UINavigationControllerDelegate {
private struct AssociatedKeys {
static var currentCompletioObjectHandle = "currentCompletioObjectHandle"
}
typealias Completion = @convention(block) (UIViewController)->()
var completionBlock:Completion?{
get{
let chBlock = unsafeBitCast(objc_getAssociatedObject(self, &AssociatedKeys.currentCompletioObjectHandle), Completion.self)
return chBlock as Completion
}set{
if let newValue = newValue {
let newValueObj : AnyObject = unsafeBitCast(newValue, AnyObject.self)
objc_setAssociatedObject(self, &AssociatedKeys.currentCompletioObjectHandle, newValueObj, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)
}
}
}
func popToViewController(animated: Bool,comp:Completion){
if (self.delegate == nil){
self.delegate = self
}
completionBlock = comp
self.popViewControllerAnimated(true)
}
func pushViewController(viewController: UIViewController, comp:Completion) {
if (self.delegate == nil){
self.delegate = self
}
completionBlock = comp
self.pushViewController(viewController, animated: true)
}
public func navigationController(navigationController: UINavigationController, didShowViewController viewController: UIViewController, animated: Bool){
if let comp = completionBlock{
comp(viewController)
completionBlock = nil
self.delegate = nil
}
}
}
viewDidAppear:animated:允许您每次视图控制器出现在屏幕上时执行代码（viewDidLoad仅在第一次加载视图控制器时执行）。 - Moxy-(void)viewDidAppear:(BOOL)animated吗？ - George