UIScrollView中的手势

UIScrollView自带了两个手势,分别为:

UIPanGestureRecognizer

UIPinchGestureRecognizer

他们都是readonly的.

 

监听UIPanGestureRecognizer

手势是UIPanGestureRecognizer的属性,我们可以使用KVO来进行监听.

#import "RootViewController.h"#define WIDTH    self.view.frame.size.width#define HEIGHT   self.view.frame.size.height@interface RootViewController ()
     
      @property (nonatomic, strong) UIScrollView   *scrollView;@end@implementation RootViewController- (void)viewDidLoad{    [super viewDidLoad];        _scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, WIDTH, HEIGHT)];    _scrollView.contentSize = CGSizeMake(WIDTH, HEIGHT * 3);    [self.view addSubview:_scrollView];        [_scrollView addObserver:self                  forKeyPath:@"panGestureRecognizer.state"                     options:NSKeyValueObservingOptionNew                     context:nil];}-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{    // 监听pan手势开始    if (_scrollView.panGestureRecognizer.state == UIGestureRecognizerStateBegan)    {        NSLog(@"UIGestureRecognizerStateBegan");    }        // 监听pan手势值改变    if (_scrollView.panGestureRecognizer.state == UIGestureRecognizerStateChanged)    {        NSLog(@"UIGestureRecognizerStateChanged");    }        // 监听pan手势结束    if (_scrollView.panGestureRecognizer.state == UIGestureRecognizerStateEnded)    {        NSLog(@"UIGestureRecognizerStateEnded");    }}- (void)dealloc{    [_scrollView removeObserver:self                     forKeyPath:@"panGestureRecognizer.state"];}@end
     

核心代码如下:

本人在测试的时候发现,一个完整的手势事件,一般情况下,手势值的改变是会执行多次的,而UIScrollview中的pan手势处理过后,手势开始,手势值改变以及手势结束,均只执行一回.

 

添加UISwipeGestureRecognizer手势

我们可以给UIScrollview添加UISwipeGestureRecognizer手势来判断是往哪个方向轻轻滑动了.

#import "RootViewController.h"#import "GestureView.h"@interface RootViewController ()
     
      @end@implementation RootViewController- (void)viewDidLoad{    [super viewDidLoad];    #define WIDTH    self.view.frame.size.width#define HEIGHT   self.view.frame.size.height        UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];    scrollView.backgroundColor = [UIColor grayColor];    scrollView.contentSize = CGSizeMake(WIDTH, HEIGHT*3);    [self.view addSubview:scrollView];        UISwipeGestureRecognizer *up = \        [[UISwipeGestureRecognizer alloc] initWithTarget:self                                                  action:@selector(swipeEvent:)];    up.direction = UISwipeGestureRecognizerDirectionUp;    up.delegate = self;    [scrollView addGestureRecognizer:up];        UISwipeGestureRecognizer *down = \    [[UISwipeGestureRecognizer alloc] initWithTarget:self                                              action:@selector(swipeEvent:)];    down.direction = UISwipeGestureRecognizerDirectionDown;    down.delegate = self;    [scrollView addGestureRecognizer:down];}- (void)swipeEvent:(UISwipeGestureRecognizer *)gesture{    NSLog(@"%@", gesture);}- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{    return YES;}@end
     

我直接将手势对象添加进category中,运行时关联上手势对象:

UIScrollView+Swipe.h + UIScrollView+Swipe.m

#import 
     
      typedef enum {    E_UP    = 0x1000,    E_DOWN,} EDirection;@protocol UIScrollViewSwipeProtocol 
      
       - (void)swipeDirection:(EDirection)direction;@end@interface UIScrollView (Swipe)@property (nonatomic, assign)      id
       
          swipeProtocol;@property (nonatomic, strong, readonly) UISwipeGestureRecognizer *upGesture;@property (nonatomic, strong, readonly) UISwipeGestureRecognizer *downGesture;- (void)activateSwipeGesture;- (void)cancelSwipeGesture;@end
       
      
     

#import "UIScrollView+Swipe.h"#import 
     
      @interface UIScrollView ()
      
       @property (nonatomic, strong, readwrite) UISwipeGestureRecognizer *upGesture;@property (nonatomic, strong, readwrite) UISwipeGestureRecognizer *downGesture;@endstatic char swipeProtocolFlag;static char upGestureFlag;static char downGestureFlag;@implementation UIScrollView (Swipe)- (id
       
        )swipeProtocol{    return objc_getAssociatedObject(self, &swipeProtocolFlag);}- (void)setSwipeProtocol:(id
        
         )swipeProtocol{    objc_setAssociatedObject(self, &swipeProtocolFlag,                             swipeProtocol, OBJC_ASSOCIATION_ASSIGN);}- (void)setUpGesture:(UISwipeGestureRecognizer *)upGesture{    objc_setAssociatedObject(self, &upGestureFlag,                             upGesture, OBJC_ASSOCIATION_RETAIN_NONATOMIC);}- (UISwipeGestureRecognizer *)upGesture{    return objc_getAssociatedObject(self, &upGestureFlag);}- (void)setDownGesture:(UISwipeGestureRecognizer *)downGesture{    objc_setAssociatedObject(self, &downGestureFlag,                             downGesture, OBJC_ASSOCIATION_RETAIN_NONATOMIC);}- (UISwipeGestureRecognizer *)downGesture{    return objc_getAssociatedObject(self, &downGestureFlag);}- (void)activateSwipeGesture{    if (self.upGesture == nil)    {        self.upGesture = \        [[UISwipeGestureRecognizer alloc] initWithTarget:self                                                  action:@selector(swipeGestureEvents:)];        self.upGesture.direction = UISwipeGestureRecognizerDirectionUp;        self.upGesture.delegate = self;        [self addGestureRecognizer:self.upGesture];    }        if (self.downGesture == nil)    {        self.downGesture = \        [[UISwipeGestureRecognizer alloc] initWithTarget:self                                                  action:@selector(swipeGestureEvents:)];        self.downGesture.direction = UISwipeGestureRecognizerDirectionDown;        self.downGesture.delegate = self;        [self addGestureRecognizer:self.downGesture];    }}- (void)swipeGestureEvents:(UISwipeGestureRecognizer *)gesture{    if (self.swipeProtocol)    {        if (self.downGesture == gesture)        {            [self.swipeProtocol swipeDirection:E_DOWN];        }                if (self.upGesture == gesture)        {            [self.swipeProtocol swipeDirection:E_UP];        }    }}- (void)cancelSwipeGesture{    [self removeGestureRecognizer:self.upGesture];    [self removeGestureRecognizer:self.downGesture];    self.upGesture   = nil;    self.downGesture = nil;}- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{    return YES;}@end
        
       
      
     

然后这么使用即可:),so easy!