tap是指轻触手势。类似鼠标操作的点击。从iOS 3.2版本开始支持完善的手势api:
- tap:轻触
- long press:在一点上长按
- pinch:两个指头捏或者放的操作
- pan:手指的拖动
- swipe:手指在屏幕上很快的滑动
- rotation:手指反向操作
这为开发者编写手势识别操作,提供了很大的方便,想想之前用android写手势滑动的代码(编写android简单的手势切换视图示例 ),尤其感到幸福。
这里写一个简单的tap操作。在下面视图的蓝色视图内增加对tap的识别:
?
当用手指tap蓝色视图的时候,打印日志输出:
代码很简单,首先要声明tap的recognizer:
UITapGestureRecognizer *recognizer=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapFrom:)];?
[infoView addGestureRecognizer:recognizer];?
[recognizer release];
在这里:
- initWithTarget:self,要引用到Controller,因为一般这部分代码写在controller中,用self;
- action:@selector(handleTapFrom:),赋值一个方法名,用于当手势事件发生后的回调;
- [infoView addGestureRecognizer:recognizer],为view注册这个手势识别对象,这样当手指在该视图区域内,可引发手势,之外则不会引发
对应的回调方法:
-(void)handleTapFrom:(UITapGestureRecognizer *)recognizer{?
??? NSLog(@">>>tap it");?
}
controller相关方法完整的代码(包含了一些与本文无关的视图构建代码):
// Implement loadView to create a view hierarchy programmatically,
without using a nib.?
- (void)loadView {?
???
//去掉最顶端的状态拦?
???
[[UIApplication sharedApplication] setStatusBarHidden:YES
withAnimation: UIStatusBarAnimationSlide];?
????
??? UIImage
*image=[UIImage imageNamed:@"3.jpg"];?
????
???
//创建背景视图?
???
self.view=[[UIView alloc] initWithFrame:[[UIScreen mainScreen]
applicationFrame]];?
??? UIImageView
*backgroudView=[[UIImageView alloc]
initWithImage:image];?
??? [self.view
addSubview:backgroudView];?
????
???
?
????
??? UIView
*bottomView=[[UIView alloc]?
initWithFrame:CGRectMake(0, 1024-70, 768,
70)];?
???
bottomView.backgroundColor=[UIColor
grayColor];?
???
bottomView.alpha=0.8;?
????
??? //UIButton
*backButton=[[UIButton alloc] initWithFrame:CGRectMake(10, 10, 100,
40)];?
??? UIButton
*backButton=[UIButton buttonWithType:
UIButtonTypeRoundedRect];?
??? [backButton
setTitle:@"ok"
forState:UIControlStateNormal];?
???
backButton.frame=CGRectMake(10, 15, 100,
40);?
????
??? [bottomView
addSubview:backButton];?
????
??? [self.view
addSubview:bottomView];?
????
??? UIView
*infoView=[[UIView alloc] initWithFrame:CGRectMake(200, 700,
768-400, 70)];?
???
infoView.backgroundColor=[UIColor
blueColor];?
???
infoView.alpha=0.6;?
???
infoView.layer.cornerRadius=6;?
???
infoView.layer.masksToBounds=YES;?
??? [self.view
addSubview:infoView];?
????
???
UITapGestureRecognizer *recognizer=[[UITapGestureRecognizer alloc]
initWithTarget:self
action:@selector(handleTapFrom:)];?
??? [infoView
addGestureRecognizer:recognizer];?
??? [recognizer
release];?
}
-(void)handleTapFrom:(UITapGestureRecognizer
*)recognizer{?
???
NSLog(@">>>tap
it");?
}
?
?
?
?
翻页效果,类似下面的样子:
在电子书应用中会很常见。这里需要两个要点:
- 翻页动画
- 手势上下轻扫(swipe)的处理
?
先说一下轻扫(swipe)的实现,可以参考编写简单的手势示例:Tap 了解手势种类。
在viewDidLoad方法中注册了对上、下、左、右四个方向轻松的处理方法:
- (void)viewDidLoad {?
????
??? UISwipeGestureRecognizer *recognizer;?
????
??? recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];?
??? [recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];?
??? [[self view] addGestureRecognizer:recognizer];?
??? [recognizer release];?
????
??? recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];?
??? [recognizer setDirection:(UISwipeGestureRecognizerDirectionUp)];?
??? [[self view] addGestureRecognizer:recognizer];?
??? [recognizer release];?
????
??? recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];?
??? [recognizer setDirection:(UISwipeGestureRecognizerDirectionDown)];?
??? [[self view] addGestureRecognizer:recognizer];?
??? [recognizer release];?
????
??? recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];?
??? [recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];?
??? [[self view] addGestureRecognizer:recognizer];?
??? [recognizer release];?
????
????
??? [super viewDidLoad];?
可以看到,都是同一个方法,handleSwipeFrom。
在该方法中,再识别具体是哪个方向的轻扫手势,比如判断是向下的轻扫:
-(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer {?
??? NSLog(@"Swipe received.");?
????
??? if (recognizer.direction==UISwipeGestureRecognizerDirectionDown) {?
??????? NSLog(@"swipe down");
判断是向上的轻扫:
if (recognizer.direction==UISwipeGestureRecognizerDirectionUp) {?
??? NSLog(@"swipe up");
有关动画的处理,比如向下(往回)翻页,类似这样:
[UIView beginAnimations:@"animationID" context:nil];?
[UIView setAnimationDuration:0.7f];?
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];?
[UIView setAnimationRepeatAutoreverses:NO];?
[UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES];[currentView removeFromSuperview];?
[self.view addSubview:contentView];[UIView commitAnimations];
向上(向前)翻页,只需改为:
[UIView beginAnimations:@"animationID" context:nil];?
[UIView setAnimationDuration:0.7f];?
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];?
[UIView setAnimationRepeatAutoreverses:NO];?
[UIView setAnimationTransition:UIViewAnimationTransitionCurlUp ?forView:self.view cache:YES];[currentView removeFromSuperview];?
[self.view addSubview:contentView];[UIView commitAnimations];
如果是电子书,还需要考虑一个问题,就是有多个页面(图形),比如50页。那么需要有一个数据结构来保存这些页面的图片路径:
- objc数据结构,比如数组
- sqlite数据库表
这样,写一套翻页代码和加载什么图形之间就可以解耦。
本文示例使用的是数组,类似这样:
pages=[[NSArray alloc] initWithObjects:@"1.jpg",@"2.jpg",@"3.jpg",@"4.jpg",@"5.jpg",@"6.jpg",?
???????????????? nil];
图片保存在resources下。
为了能让上页下页翻页的时候找到关联的页面,采用了如下机制:
- 将图片封装为UIImageView显示
- 可以为UIImageView设置一个tag值,值为数组下标+1
- 这样,上级view有方法能根据tag查询到UIImageView,比如:UIView *currentView=[self.view viewWithTag:currentTag];
- 设置一个成员变量currentTag保存当前的tag值
比如这样,当应用加载的时候显示第一页:
??? currentTag=1;?
????
??? NSString *path = [[NSBundle mainBundle] pathForResource:@"pageflip1" ofType:@"mp3"];?
??? player=[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];?
????
??? //[[UIApplication sharedApplication] setStatusBarHidden:YES animated:NO];?
??? [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation: UIStatusBarAnimationSlide];?
??? UIImageView *contentView = [[UIImageView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];??
??? [contentView setImage:[UIImage imageNamed:[pages objectAtIndex:(currentTag-1)]]];??
??? [contentView setUserInteractionEnabled:YES];?
??? contentView.tag=currentTag;
在翻页时的处理:
if (currentTag<[pages count])
{?
??? UIView
*currentView=[self.view
viewWithTag:currentTag];?
???
currentTag++;?
????
??? UIImageView
*contentView = [[UIImageView alloc] initWithFrame:[[UIScreen
mainScreen] applicationFrame]];?
??? [contentView
setImage:[UIImage imageNamed:[pages
objectAtIndex:(currentTag-1)]]];??
??? [contentView
setUserInteractionEnabled:YES];?
???
contentView.tag=currentTag;?
????
??? [UIView
beginAnimations:@"animationID"
context:nil];?
??? [UIView
setAnimationDuration:0.7f];?
??? [UIView
setAnimationCurve:UIViewAnimationCurveEaseInOut];?
??? [UIView
setAnimationRepeatAutoreverses:NO];?
??? [UIView
setAnimationTransition:UIViewAnimationTransitionCurlUp
forView:self.view cache:YES];?
????
??? [currentView
removeFromSuperview];?
??? [self.view
addSubview:contentView];?
????
??? [UIView
commitAnimations];