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手势识别在ios上非常重要,手势操作移动设备的重要特征,极大的增加了移动设备使用便捷性。
1、uigesturerecognizer介绍
手势识别在ios上非常重要，手势操作移动设备的重要特征，极大的增加了移动设备使用便捷性。
ios系统在3.2以后，为方便开发这使用一些常用的手势，提供了uigesturerecognizer类。手势识别uigesturerecognizer类是个抽象类，下面的子类是具体的手势，开发这可以直接使用这些手势识别。
上面的手势对应的操作是：
uigesturerecognizer的继承关系如下：
2、使用手势的步骤
使用手势很简单，分为两步：
创建手势实例。当创建手势时，指定一个回调方法，当手势开始，改变、或结束时，回调方法被调用。
添加到需要识别的view中。每个手势只对应一个view，当屏幕触摸在view的边界内时，如果手势和预定的一样，那就会回调方法。
ps：一个手势只能对应一个view，但是一个view可以有多个手势。
建议在真机上运行这些手势,模拟器操作不太方便，可能导致你认为手势失效。
3、pan 拖动手势：
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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];
新建一个imageview，然后添加手势
回调方法：
- (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缩放手势
uipinchgesturerecognizer *pinchgesturerecognizer = [[uipinchgesturerecognizer alloc]
initwithtarget:self
action:@selector(handlepinch:)];<p class="p1">[<span class="s1">snakeimageview</span> <span class="s2">addgesturerecognizer</span>:pinchgesturerecognizer];</p>
- (void) handlepinch:(uipinchgesturerecognizer*) recognizer
{
recognizer.view.transform = cgaffinetransformscale(recognizer.view.transform, recognizer.scale, recognizer.scale);
recognizer.scale = 1;
}
5、rotation旋转手势
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;
}
添加了这几个手势后，运行看效果，程序中的imageview放了一个
/^\/^\
_|__| o|
\/ /~ \_/ \
\____|__________/ \
\_______ \
`\ \ \
| | \
/ / \
/ / \\
/ / \ \
/ / \ \
/ / _----_ \ \
/ / _-~ ~-_ | |
( ( _-~ _--_ ~-_ _/ |
\ ~-____-~ _-~ ~-_ ~-_-~ /
~-_ _-~ ~-_ _-~
~--______-~ ~-___-~
的图片，在模拟器上拖动是没问题的。缩放和旋转有点问题，估计是因为在模拟器上的模拟的两个接触点距离在imageview的边界外了，所以操作无效果。
建议在真机上运行这个手势。
在模拟器上缩放和选择的操作技巧：
可以把imageview的frame值设置大一点，按住alt键，按下触摸板(不按下不行)，这样就可以旋转和缩放了。
6、添加第二个imagview并添加手势
记住：一个手势只能添加到一个view，两个view当然要有两个手势的实例了
- (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]];
}
多添加了一条龙的view，两个view都能接收上面的三种手势。运行效果如下：
7、拖动(pan手势)速度(以较快的速度拖放后view有滑行的效果)
如何实现呢？
- (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];
}
代码实现解析：
运行后，快速拖动图像view放开会看到view还会在原来的方向滑行一段路。
8、同时触发两个view的手势
手势之间是互斥的，如果你想同时触发蛇和龙的view，那么需要实现协议
uigesturerecognizerdelegate，
@interface viewcontroller : uiviewcontroller<uigesturerecognizerdelegate> @end
并在协议这个方法里返回yes。
-(bool)gesturerecognizer:(uigesturerecognizer *)gesturerecognizer shouldrecognizesimultaneouslywithgesturerecognizer:(uigesturerecognizer *)othergesturerecognizer
{
return yes;
}
把self作为代理设置给手势：
pangesturerecognizer.delegate = self; pinchgesturerecognizer.delegate = self; rotaterecognizer.delegate = self;
这样可以同时拖动或旋转缩放两个view了。
9、tap点击手势
这里为了方便看到tap的效果，当点击一下屏幕时，播放一个声音。
为了播放声音，我们加入avfoundation.framework这个框架。
- (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;
}
我会在最后例子代码给出完整代码，添加手势的步骤和前面一样的。
#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];
}
运行，点一下某个图，就会播放一个咬东西的声音。
不过这个点击播放声音有点缺陷，就是在慢慢拖动的时候也会播放。这使得两个手势重合了。怎么解决呢？使用手势的：
requiregesturerecognizertofail方法。
10、手势的依赖性
在viewdidload的循环里添加这段代码：
[taprecognizer requiregesturerecognizertofail:pangesturerecognizer];
意思就是，当如果pan手势失败，就是没发生拖动，才会出发tap手势。这样如果你有轻微的拖动，那就是pan手势发生了。tap的声音就不会发出来了。
11、自定义手势
自定义手势继承：uigesturerecognizer，实现下面的方法：
– touchesbegan:withevent: – touchesmoved:withevent: – touchesended:withevent: - touchescancelled:withevent:
新建一个类，继承uigesturerecognizer，代码如下：
.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;
// 确认方向改变了
if (self.lastdirection == directionunknown ||
(self.lastdirection == directionleft && curdirection == directionright) ||
(self.lastdirection == directionright && curdirection == directionleft)) {
// 挠痒次数
self.ticklecount++;
self.curticklestart = ticklepoint;
self.lastdirection = curdirection;
// 一旦挠痒次数超过指定数，设置手势为结束状态
// 这样回调函数会被调用。
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
调用自定义手势和上面一样，回到这样写：
- (void)handlehappy:(happygesturerecognizer *)recognizer{
[self.heheplayer play];
}
手势成功后播放呵呵笑的声音。
在真机上运行，按住某个view，快速左右拖动，就会发出笑的声音了。
代码解析：
先获取起始坐标：curticklestart
通过和ticklepoint的x值对比，得出当前的放下是向左还是向右。再算出移动的x的值是否比move_amt_per_tickle距离大，如果太则返回。
再判断是否有三次是不同方向的动作，如果是则手势结束，回调。
源代码：。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。
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