# Three Methods of left-sliding pop in IOS-navigation

# Three Methods of left-sliding pop in IOS-navigation
Three methods of left-sliding pop in IOS-navigation: pop Method

If we do not customize the back button in navigation, we can directly use the left-sliding pop method that comes with the system. However, if we customize the back button, we needself.navigationController.interactivePopGestureRecognizerThis attribute is set.

Key code
_ Weak typeof (self) weakSelf = self;
Self. navigationController. interactivepopgsturerecognizer. delegate =
WeakSelf;

The following is the instance code:

(Inheriting the AbeViewController class, you can use the pop method that comes with the system .)

# Import "AbeViewController. h" @ interface AbeViewController ()
  
   
@ End @ implementation AbeViewController-(void) viewDidLoad {[super viewDidLoad];}-(void) viewDidAppear :( BOOL) animated {// **************** method 1 ****************//// set sliding rollback _ weak typeof (self) weakSelf = self; self. navigationController. interactivepopgsturerecognizer. delegate = weakSelf; // determines whether it is the first view if (self. navigationController & [self. navigationController. viewControllers count] = 1) {self. navigationController. interactivepopgsturerecognizer. enabled = NO ;}} # pragma mark-UIGestureRecognizerDelegate // **************** method 1 ****************/ /-(BOOL) gestureRecognizerShouldBegin :( UIGestureRecognizer *) gestureRecognizer {return YES;} @ end
  

Custom left-sliding edge gesture Method

A gesture method is implemented, and pop is triggered when the gesture method is used.

The following is the instance code:

(Inheriting the AbeViewController class, you can use the pop method of the custom left-sliding edge gesture .)

# Import "AbeViewController. h" @ interface AbeViewController ()
  
   
@ End @ implementation AbeViewController-(void) viewDidLoad {[super viewDidLoad];}-(void) viewDidAppear :( BOOL) animated {// ************** method 2 ****************** // UIScreenEdgePanGestureRecognizer * edgePanGestureRecognizer = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget: self action: @ selector (edgePanGesture :)]; edgePanGestureRecognizer. delegate = self; edgePanGestureRecognizer. edges = UIRectEdgeLeft; [self. view addGestureRecognizer: edgePanGestureRecognizer];}-(void) didReceiveMemoryWarning {[super didreceivemorywarning];} # pragma mark-private method // ************** method 2 ***************** //-(void) edgePanGesture :( UIScreenEdgePanGestureRecognizer *) edgePanGestureRecognizer {[self. navigationController popViewControllerAnimated: YES];} # pragma mark-UIGestureRecognizerDelegate // **************** method 2 ****************/ /-(BOOL) gestureRecognizerShouldBegin :( UIGestureRecognizer *) gestureRecognizer {if (self. navigationController & [self. navigationController. viewControllers count] = 1) {return NO;} return YES;} @ end
  

Custom view left-shift pop

In the view, the pop method is triggered by moving left at any position.
In fact, a UIPanGestureRecognizer gesture is created and then triggered by the gesture.

Knowledge point:

[PanGestureRecognizer locationInView: XX] obtain the CGPoint of the pan gesture.
PanGestureRecognizer. state pan status
Self. interactivepopgsturerecognizer. enabled = NO; Native left slide is invalid

The following is the instance code:

(Inheriting the ABENavViewController class, you can use the pop method of the custom view left sliding gesture; ABENavViewController is the subclass of UINavigationController)

# Import "ABENavViewController. h "@ interface ABENavViewController () @ property (strong, nonatomic) Comment * comment; @ property (strong, nonatomic) UIImageView * backView; @ property (strong, nonatomic) NSMutableArray * backImgs; @ property (assign) CGPoint panBeginPoint; @ property (assign) CGPoint panEndPoint; @ end @ implementation ABENavViewController-(instancetype) initWithNibName :( NSString *) nibNameOrNil bundle :( NSBundle *) nibBundleOrNil {self = [super initWithNibName: nibNameOrNil bundle: nibBundleOrNil]; if (self) {// initlization} return self ;}- (void) loadView {[super loadView]; [self initilization];}-(void) viewDidLoad {[super viewDidLoad]; [self loadBaseUI];}-(void) initilization {self. backImgs = [[NSMutableArray alloc] init];}-(void) loadBaseUI {// The native method is invalid self. interactivepopgsturerecognizer. enabled = NO; // set the gesture self. panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget: self action: @ selector (panGestureRecognizerAction :)]; [self. view addGestureRecognizer: self. panGestureRecognizer];} # pragma mark-public method-(void) pushViewController :( UIViewController *) viewController animated :( BOOL) animated {// encrypt ([UIScreen mainScreen]. bounds. size, YES, 1.0); [[UIApplication sharedApplication]. keyWindow. layer renderInContext: UIGraphicsGetCurrentContext ()]; UIImage * img = UIGraphicsGetImageFromCurrentImageContext (); UIGraphicsEndImageContext (); [self. backImgs addObject: img]; [super pushViewController: viewController animated: animated];}-(UIViewController *) Updated :( BOOL) animated {[_ backImgs removeLastObject]; return [super ready: animated] ;}# pragma mark-private method-(void) panGestureRecognizerAction :( UIPanGestureRecognizer *) panGestureRecognizer {if ([self. viewControllers count] = 1) {return;} if (panGestureRecognizer. state = UIGestureRecognizerStateBegan) {NSLog (@ "slide start"); // stores the position self where the slide starts. panBeginPoint = [panGestureRecognizer locationInView: [UIApplication sharedApplication]. keyWindow]; // insert an image [self insertLastViewFromSuperView: self. view. superview];} else if (panGestureRecognizer. state = UIGestureRecognizerStateEnded) {NSLog (@ "sliding end"); // store data self. panEndPoint = [panGestureRecognizer locationInView: [UIApplication sharedApplication]. keyWindow]; if (_ panEndPoint. x-_ panBeginPoint. x)> 50) {[UIView animateWithDuration: 0.3 animations: ^ {[self moveNavigationViewWithLenght: [UIScreen mainScreen]. bounds. size. width];} completion: ^ (BOOL finished) {[self removeLastViewFromSuperView]; [self moveNavigationViewWithLenght: 0]; [self popViewControllerAnimated: NO];} else {[UIView animateWithDuration: 0.3 animations: ^ {[self failed: 0] ;}} else {// Add the moving effect CGFloat panLength = ([panGestureRecognizer locationInView: [UIApplication sharedApplication]. keyWindow]. x-_ panBeginPoint. x); if (panLength> 0) {[self moveNavigationViewWithLenght: panLength] ;}} /*** mobile view ** @ param lenght: length of movement */-(void) moveNavigationViewWithLenght :( CGFloat) lenght {// set the image position self. view. frame = CGRectMake (lenght, self. view. frame. origin. y, self. view. frame. size. width, self. view. frame. size. height); // dynamic shadow _ backView. alpha = (lenght/[UIScreen mainScreen]. bounds. size. width) * 2/3 + 0.33;}/*** superView of the top-level image in the illustration ** @ param superView image */-(void) insertLastViewFromSuperView :( UIView *) superView {// Insert the upper-level view background if (_ backView = nil) {_ backView = [[UIImageView alloc] initWithFrame: [UIScreen mainScreen]. bounds]; _ backView. image = [_ backImgs lastObject];} [self. view. superview insertSubview: _ backView belowSubview: self. view];}/*** remove the image of the previous level */-(void) removeLastViewFromSuperView {[_ backView removeFromSuperview]; _ backView = nil;} @ end