原文 http://blog.csdn.net/crayondeng/article/details/8760134
UIGestureRecognizer 類
該類擁有一系列子類，每個子類都用於識別某類指定的手勢。它們是：
UITapGestureRecognizer – “輕擊”手勢。可以配置爲“單擊”和“連擊”的識別。
UIPinchGestureRecognizer –“捏合”手勢。該手勢通常用於縮放視圖或改變可視組件的大小。
UIPanGestureRecognizer – “平移”手勢。識別拖拽或移動動作。
UISwipeGestureRecognizer – “輕掃”手勢。當用戶從屏幕上劃過時識別爲該手勢。可以指定該動作的方向（上、下、左、右）。
UIRotationGestureRecognizer – “轉動”手勢。用戶兩指在屏幕上做相對環形運動。
UILongPressGestureRecognizer – “長按”手勢。使用一指或多指觸摸屏幕並保持一定時間。
這些手勢識別器必需和視圖通過addGestureRecognizer:方法聯繫在一起。識別器必需指定一個響應方法以便發生指定手勢時進行調用。removeGestureRecognizer:方法可以將識別器從視圖中移出，方法參數指定要移除的識別器。
下面通過一個實例程序來分別介紹這些手勢，在一個視圖中增加一個UIImageView控件，添加一個圖像。對圖像的操作都基於此視圖中進行。分別對這個圖像使用這些手勢。
一、首先在一個視圖中添加一個imageview控件，用以添加一個圖像。
self.productImageView.image = [UIImage imageNamed:@"iPhone.jpg"];
二、tap 手勢 （輕擊）
說明：在單擊中，實現的是視圖恢復，在雙擊中實現的是視圖放大/縮小一倍。
//輕點
// 單擊
UITapGestureRecognizer *SingleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(resetImage:)];
SingleTapGesture.numberOfTapsRequired = 1;//tap次數
[self.view addGestureRecognizer:SingleTapGesture];
// 雙擊
UITapGestureRecognizer *doubleTapGesture;
doubleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTapFrom)];
doubleTapGesture.numberOfTapsRequired = 2;
[self.view addGestureRecognizer:doubleTapGesture];
// 關鍵在這一行，如果雙擊確定偵測失敗才會觸發單擊
[SingleTapGesture requireGestureRecognizerToFail:doubleTapGesture];
響應方法
//單擊恢復視圖
- (void)resetImage:(UITapGestureRecognizer *)recognizer
{
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.3];
// 恆等變換. beginAnimation 和 commitAnimation 間的操作爲動畫過程
self.productImageView.transform = CGAffineTransformIdentity;
[self.productImageView setCenter:CGPointMake(self.view.frame.size.height/2, self.view.frame.size.width/2)];
[UIView commitAnimations];
}
//雙擊實現放大和縮小一倍
- (void) handleDoubleTapFrom {
if (flag == YES) {
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.3];
[self.productImageView setFrame:CGRectMake(
self.productImageView.frame.origin.x -self.productImageView.frame.size.width / 2,
self.productImageView.frame.origin.y - self.productImageView.frame.size.height / 2,
2 * self.productImageView.frame.size.width,
2 * self.productImageView.frame.size.height)];
[UIView commitAnimations];
flag = NO;
}
else {
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.3];
[self.productImageView setFrame:CGRectMake(self.productImageView.frame.origin.x+self.productImageView.frame.size.width/4, self.productImageView.frame.origin.y + self.productImageView.frame.size.height/4, self.productImageView.frame.size.width/2, self.productImageView.frame.size.height/2)];
[UIView commitAnimations];
flag = YES;
}
}
特別說明這個語句：
[SingleTapGesture requireGestureRecognizerToFail:doubleTapGesture];
有些手勢其實是互相關聯的，例如 Tap 與 LongPress、Swipe與 Pan，或是 Tap 一次與Tap 兩次。當一個 UIView 同時添加兩個相關聯的手勢時，到底我這一下手指頭按的要算是 Tap 還是 LongPress？如果照預設作法來看，只要先滿足條件的就會跳出並呼叫對應方法，舉例來說，如果同時註冊了 Pan 和 Swipe，只要手指頭一移動就會觸發 Pan 然後跳出，因而永遠都不會發生 Swipe；單點與雙點的情形也是一樣，永遠都只會觸發單點，不會有雙點。那麼這個問題有解嗎？答案是肯定的，UIGestureRecognizer 有個方法叫做requireGestureRecognizerToFail，他可以指定某一個 recognizer，即便自己已經滿足條件了，也不會立刻觸發，會等到該指定的 recognizer 確定失敗之後才觸發。
二、pinch 手勢 （捏合縮放）
說明：在模擬器中 按住alt+鼠標左鍵即可出現雙指觸摸屏幕。
//捏合縮放
UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchView:)];
[self.view addGestureRecognizer:pinchGesture];
響應方法 （以下提供了兩種縮放響應方法）
// 處理捏合縮放手勢
- (void) pinchView:(UIPinchGestureRecognizer *)pinchGestureRecognizer
{
UIView *view = self.productImageView;
if (pinchGestureRecognizer.state == UIGestureRecognizerStateBegan || pinchGestureRecognizer.state == UIGestureRecognizerStateChanged) {
view.transform = CGAffineTransformScale(view.transform, pinchGestureRecognizer.scale, pinchGestureRecognizer.scale);
pinchGestureRecognizer.scale = 1;
}
}
- (void)scaleImage:(UIPinchGestureRecognizer *)recognizer
{
if([recognizer state] == UIGestureRecognizerStateEnded) {
// 如果Pinch 手勢結束，重置 previousScale 爲 1.0
self.previousScale = 1.0;
return;
}
CGFloat newScale = [recognizer scale]-self.previousScale +1.0;
CGAffineTransform currentTransformation = self.productImageView.transform;
// CGAffineTransformScale(currentTransformation, 1, 1) 變換保持原大小
CGAffineTransform newTransform = CGAffineTransformScale(currentTransformation, newScale, newScale);
// perform the new transform
self.productImageView.transform = newTransform;
self.previousScale = [recognizer scale];
}
三、pan 手勢 （平移）
//平移
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panView:)];
[panGesture setMinimumNumberOfTouches:1];
[panGesture setMaximumNumberOfTouches:1];
[self.view addGestureRecognizer:panGesture];
響應方法
// 處理拖拉手勢
- (void) panView:(UIPanGestureRecognizer *)panGestureRecognizer
{
UIView *view = self.productImageView;
if (panGestureRecognizer.state == UIGestureRecognizerStateBegan || panGestureRecognizer.state == UIGestureRecognizerStateChanged) {
CGPoint translation = [panGestureRecognizer translationInView:view.superview];
[view setCenter:(CGPoint){view.center.x + translation.x, view.center.y + translation.y}];
[panGestureRecognizer setTranslation:CGPointZero inView:view.superview];
}
}
四、rotate 手勢 （旋轉）
//旋轉
UIRotationGestureRecognizer *rotationGesture = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotateView:)];
[self.view addGestureRecognizer:rotationGesture];
響應方法
// 處理旋轉手勢
- (void) rotateView:(UIRotationGestureRecognizer *)rotationGestureRecognizer
{
UIView *view = self.productImageView;
if (rotationGestureRecognizer.state == UIGestureRecognizerStateBegan || rotationGestureRecognizer.state == UIGestureRecognizerStateChanged) {
view.transform = CGAffineTransformRotate(view.transform, rotationGestureRecognizer.rotation);
[rotationGestureRecognizer setRotation:0];
}
}
最後還有一個要處理的就是模擬器的橫向擺放。
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return ((interfaceOrientation == UIInterfaceOrientationLandscapeRight) || (interfaceOrientation == UIInterfaceOrientationLandscapeLeft));
}