主要的实现思路就是：自定义导航栏，利用runtime运行时机制，获取系统的手势target 和action，然后将系统的手势加到导航控制器的视图，实现全屏返回；
OC操作如下：
1.自定义导航栏，导入运行时框架，遵守代理协议：UIGestureRecognizerDelegate
#import <objc/runtime.h>
@interface MainNavVC : UINavigationController<UIGestureRecognizerDelegate>
2.在 viewDidLoad 中实现如下代码：
// 1.使用运行时，打印手势中的所有属性
// unsigned int count = 0;
// Ivar * ivars = class_copyIvarList([UIGestureRecognizer class], &count);
// for (int i = 0; i < count; i++) {
// const char * name = ivar_getName(ivars[i]);
// NSLog(@"%s",name);
// }
// 2.获取当前interactivePopGestureRecognizer 中的“ _targets” 数据，取第一个；
id targets = [self.interactivePopGestureRecognizer valueForKey:@"_targets"];
id targetObjc = targets[0];
id target = [targetObjc valueForKey:@"target"];
SEL action = NSSelectorFromString(@"handleNavigationTransition:");
UIGestureRecognizer * panGes = [[UIPanGestureRecognizer alloc]initWithTarget:target action:action];
[self.view addGestureRecognizer:panGes];
另一种写法:思想还是上面的思想
（1）获取系统自带滑动手势的target对象
id target = self.interactivePopGestureRecognizer.delegate;
// 创建全屏滑动手势，调用系统自带滑动手势的target的action方法
UIGestureRecognizer * apopRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:target action:@selector(handleNavigationTransition:)];
// 设置手势代理，拦截手势触发
apopRecognizer.delegate = self;
// 给导航控制器的view添加全屏滑动手势
[self.view addGestureRecognizer:apopRecognizer];
// 禁止使用系统自带的滑动手势
self.interactivePopGestureRecognizer.enabled = NO;
（2）本地实现 handleNavigationTransition 方法：
- (void)handleNavigationTransition:(UIPanGestureRecognizer *)recognizer {
// [[self class] cancelPreviousPerformRequestsWithTarget:self selector:@selector(todoSomething:) object:recognizer];
// [self performSelector:@selector(todoSomething:) withObject:recognizer afterDelay:0.2f];
//
/**
* 稳定进度区间，让它在0.0（未完成）～1.0（已完成）之间
*/
CGFloat progress = [recognizer translationInView:recognizer.view].x / recognizer.view.bounds.size.width;
progress = MIN(1.0, MAX(0.0, progress));
NSLog(@"progress == %f",progress);
if (recognizer.state == UIGestureRecognizerStateBegan) {
NSLog(@"UIGestureRecognizerStateBegan");
}
else if (recognizer.state == UIGestureRecognizerStatePossible) {
NSLog(@"UIGestureRecognizerStatePossible");
}
else if (recognizer.state == UIGestureRecognizerStateFailed) {
NSLog(@"UIGestureRecognizerStateFailed == " );
}
else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) {
NSLog(@"UIGestureRecognizerStateEnded");
if (progress > 0.5) {
} else {
}
}
}
swift操作如下：
override func viewDidLoad() {
super.viewDidLoad()
//1.使用运行时，打印手势中所有的属性
// var count :UInt32 = 0
// let ivars = class_copyIvarList(UIGestureRecognizer.self, &count)!
// for i in 0 ..< count {
// let namep = ivar_getName(ivars[Int(i)])!
// let name = String(cString:namep)
// print(name)
// }
guard let targets = interactivePopGestureRecognizer!.value(forKey: "_targets") as? [NSObject] else {
return
}
let targetObjc = targets[0]
let target = targetObjc.value(forKey: "target")
let action = Selector(("handleNavigationTransition:"))
let panGes = UIPanGestureRecognizer(target: target, action: action)
panGes.delegate = self
view.addGestureRecognizer(panGes)
}
遵守代理协议，根控制器取消手势事件
extension HZNavigationController:UIGestureRecognizerDelegate{
func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
// 注意：只有非根控制器才有滑动返回功能，根控制器没有。
// 判断导航控制器是否只有一个子控制器，如果只有一个子控制器，肯定是根控制器
if (self.childViewControllers.count == 1) {
// 表示用户在根控制器界面，就不需要触发滑动手势，
return false;
}
// 当前页面是显示结果页，不响应滑动手势
let vc = self.childViewControllers.last!
if vc.isKind(of: UIInputViewController.self){
return false;
}
return true
}
}