// 新建一個ImageView,然後添加手勢 UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]]; snakeImageView.frame = CGRectMake(50, 50, 100, 160); UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)]; [snakeImageView addGestureRecognizer:panGestureRecognizer]; [self.view setBackgroundColor:[UIColor whiteColor]]; [self.view addSubview:snakeImageView]; // 回調方法: - (void) handlePan:(UIPanGestureRecognizer*) recognizer { CGPoint translation = [recognizer translationInView:self.view]; recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, recognizer.view.center.y + translation.y); [recognizer setTranslation:CGPointZero inView:self.view]; }
4、Pinch縮放手勢
UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)]; - (void) handlePinch:(UIPinchGestureRecognizer*) recognizer { recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale); recognizer.scale = 1; }
5、Rotation旋轉手勢
UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(handleRotate:)]; [snakeImageView addGestureRecognizer:rotateRecognizer]; - (void) handleRotate:(UIRotationGestureRecognizer*) recognizer { recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation); recognizer.rotation = 0; }
6、添加第二個ImagView並添加手勢 記住:一個手勢只能添加到一個View,兩個View當然要有兩個手勢的實例了
- (void)viewDidLoad { [super viewDidLoad]; UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]]; UIImageView *dragonImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"dragon.png"]]; snakeImageView.frame = CGRectMake(120, 120, 100, 160); dragonImageView.frame = CGRectMake(50, 50, 100, 160); [self.view addSubview:snakeImageView]; [self.view addSubview:dragonImageView]; for (UIView *view in self.view.subviews) { UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)]; UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinch:)]; UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(handleRotate:)]; [view addGestureRecognizer:panGestureRecognizer]; [view addGestureRecognizer:pinchGestureRecognizer]; [view addGestureRecognizer:rotateRecognizer]; [view setUserInteractionEnabled:YES]; } [self.view setBackgroundColor:[UIColor whiteColor]]; }
7、拖動(pan手勢)速度(以較快的速度拖放後view有滑行的效果) 如何實現呢? 1.監視手勢是否結束 2.監視觸摸的速度
- (void) handlePan:(UIPanGestureRecognizer*) recognizer { CGPoint translation = [recognizer translationInView:self.view]; recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, recognizer.view.center.y + translation.y); [recognizer setTranslation:CGPointZero inView:self.view]; if (recognizer.state == UIGestureRecognizerStateEnded) { CGPoint velocity = [recognizer velocityInView:self.view]; CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y)); CGFloat slideMult = magnitude / 200; NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult); float slideFactor = 0.1 * slideMult; // Increase for more of a slide CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor), recognizer.view.center.y + (velocity.y * slideFactor)); finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width); finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height); [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{ recognizer.view.center = finalPoint; } completion:nil]; }
代碼實現解析: 1.計算速度向量的長度(估計大部分都忘了)這些知識了。 2.如果速度向量小於200,那就會得到一個小於的小數,那麼滑行會很短 3.基於速度和速度因素計算一個終點 4.確保終點不會跑出父View的邊界 5.使用UIView動畫使view滑動到終點 運行後,快速拖動圖像view放開會看到view還會在原來的方向滑行一段路。 8、同時觸發兩個view的手勢 手勢之間是互斥的,如果你想同時觸發蛇和龍的view,那麼需要實現協議UIGestureRecognizerDelegate, 並在協議這個方法裡返回YES。
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer { return YES; }
把self作為代理設置給手勢:
panGestureRecognizer.delegate = self; pinchGestureRecognizer.delegate = self; rotateRecognizer.delegate = self;
這樣可以同時拖動或旋轉縮放兩個view了。 1 9、tap點擊手勢 這裡為了方便看到tap的效果,當點擊一下屏幕時,播放一個聲音。 為了播放聲音,我們加入AVFoundation.framework這個框架。
- (AVAudioPlayer *)loadWav:(NSString *)filename { NSURL * url = [[NSBundle mainBundle] URLForResource:filename withExtension:@"wav"]; NSError * error; AVAudioPlayer * player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error]; if (!player) { NSLog(@"Error loading %@: %@", url, error.localizedDescription); } else { [player prepareToPlay]; } return player; }
我會在最後例子代碼給出完整代碼,添加手勢的步驟和前面一樣的。
#import <UIKit/UIKit.h> #import <AVFoundation/AVFoundation.h> @interface ViewController : UIViewController<UIGestureRecognizerDelegate> @property (strong) AVAudioPlayer * chompPlayer; @property (strong) AVAudioPlayer * hehePlayer; @end - (void)handleTap:(UITapGestureRecognizer *)recognizer { [self.chompPlayer play]; }
運行,點一下某個圖,就會播放一個咬東西的聲音。 不過這個點擊播放聲音有點缺陷,就是在慢慢拖動的時候也會播放。這使得兩個手勢重合了。怎麼解決呢?使用手勢的:requireGestureRecognizerToFail方法。 10、手勢的依賴性 在viewDidLoad的循環裡添加這段代碼: 1 [tapRecognizer requireGestureRecognizerToFail:panGestureRecognizer]; 意思就是,當如果pan手勢失敗,就是沒發生拖動,才會出發tap手勢。這樣如果你有輕微的拖動,那就是pan手勢發生了。tap的聲音就不會發出來了。 11、自定義手勢 自定義手勢繼承:UIGestureRecognizer,實現下面的方法:
– touchesBegan:withEvent: – touchesMoved:withEvent: – touchesEnded:withEvent: - touchesCancelled:withEvent:
新建一個類,繼承UIGestureRecognizer,代碼如下: .h文件
#import <UIKit/UIKit.h> typedef enum { DirectionUnknown = 0, DirectionLeft, DirectionRight } Direction; @interface HappyGestureRecognizer : UIGestureRecognizer @property (assign) int tickleCount; @property (assign) CGPoint curTickleStart; @property (assign) Direction lastDirection; @end
.m文件
#import "HappyGestureRecognizer.h" #import <UIKit/UIGestureRecognizerSubclass.h> #define REQUIRED_TICKLES 2 #define MOVE_AMT_PER_TICKLE 25 @implementation HappyGestureRecognizer - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch * touch = [touches anyObject]; self.curTickleStart = [touch locationInView:self.view]; } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { // Make sure we've moved a minimum amount since curTickleStart UITouch * touch = [touches anyObject]; CGPoint ticklePoint = [touch locationInView:self.view]; CGFloat moveAmt = ticklePoint.x - self.curTickleStart.x; Direction curDirection; if (moveAmt < 0) { curDirection = DirectionLeft; } else { curDirection = DirectionRight; } if (ABS(moveAmt) < MOVE_AMT_PER_TICKLE) return; // 確認方向改變了 if (self.lastDirection == DirectionUnknown || (self.lastDirection == DirectionLeft && curDirection == DirectionRight) || (self.lastDirection == DirectionRight && curDirection == DirectionLeft)) { // 撓癢次數 self.tickleCount++; self.curTickleStart = ticklePoint; self.lastDirection = curDirection; // 一旦撓癢次數超過指定數,設置手勢為結束狀態 // 這樣回調函數會被調用。 if (self.state == UIGestureRecognizerStatePossible && self.tickleCount > REQUIRED_TICKLES) { [self setState:UIGestureRecognizerStateEnded]; } } } - (void)reset { self.tickleCount = 0; self.curTickleStart = CGPointZero; self.lastDirection = DirectionUnknown; if (self.state == UIGestureRecognizerStatePossible) { [self setState:UIGestureRecognizerStateFailed]; } } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { [self reset]; } - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { [self reset]; } @end
調用自定義手勢和上面一樣,回到這樣寫:
- (void)handleHappy:(HappyGestureRecognizer *)recognizer{ [self.hehePlayer play]; }
手勢成功後播放呵呵笑的聲音。 在真機上運行,按住某個view,快速左右拖動,就會發出笑的聲音了。 代碼解析: 先獲取起始坐標:curTickleStart 通過和ticklePoint的x值對比,得出當前的放下是向左還是向右。再算出移動的x的值是否比MOVE_AMT_PER_TICKLE距離大,如果太則返回。 再判斷是否有三次是不同方向的動作,如果是則手勢結束,回調。