ios – 如何在Xcode中跟踪多个触摸
发布时间:2020-12-15 01:41:17 所属栏目:百科 来源:网络整理
导读:最近我正在创建一个可以同时拖动多个对象的应用程序.我曾尝试使用UIPanGestureRecognizer来获取手指触摸的坐标,但我不知道哪个触摸属于哪个手指. 我需要支持四个手指同时平移而不会使用Objective-C相互干扰. 我已经搜索了一段时间的洗液,但他们显示的答案对
最近我正在创建一个可以同时拖动多个对象的应用程序.我曾尝试使用UIPanGestureRecognizer来获取手指触摸的坐标,但我不知道哪个触摸属于哪个手指.
我需要支持四个手指同时平移而不会使用Objective-C相互干扰. 我已经搜索了一段时间的洗液,但他们显示的答案对我不起作用.任何帮助,将不胜感激. 解决方法
我在相当长的一段时间内遇到了同样的问题并最终解决了它.以下是我的DrawView.m中的代码,它是UIView的子类,能够使用drawRect:支持绘图.
#import "DrawView.h" #define MAX_TOUCHES 4 @interface DrawView() { bool touchInRect[MAX_TOUCHES]; CGRect rects[MAX_TOUCHES]; UITouch *savedTouches[MAX_TOUCHES]; } @end @implementation DrawView -(id)initWithCoder:(NSCoder *)aDecoder { self = [super initWithCoder:aDecoder]; if (self) { // Initialization code self.multipleTouchEnabled = YES; for (int i=0; i<MAX_TOUCHES; i++) { rects[i] = CGRectMake(200,200,50,50); savedTouches[i] = NULL; touchInRect[i] = false; } } return self; } - (void)drawRect:(CGRect)rect { // Drawing code [[UIColor blueColor] set]; CGContextRef context = UIGraphicsGetCurrentContext(); for (int i=0; i<MAX_TOUCHES; i++) { CGContextFillRect(context,rects[i]); CGContextStrokePath(context); } } #pragma mark - Handle Touches - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { NSArray *allTouches = [touches allObjects]; for (int i=0; i<[allTouches count]; i++) { UITouch *touch = allTouches[i]; CGPoint newPoint = [touch locationInView:self]; for (int j=0; j<MAX_TOUCHES; j++) { if (CGRectContainsPoint(rects[j],newPoint) && !touchInRect[j]) { touchInRect[j] = true; savedTouches[j] = touch; break; } } } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { NSArray *allTouches = [touches allObjects]; for (int i=0; i<[allTouches count]; i++) { UITouch *touch = allTouches[i]; CGPoint newPoint = [touch locationInView:self]; for (int j=0; j<MAX_TOUCHES; j++) { if (touch == savedTouches[j]) { rects[j] = [self rectWithSize:rects[j].size andCenter:newPoint]; [self setNeedsDisplay]; break; } } } } - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { NSArray *allTouches = [touches allObjects]; for (int i=0; i<[allTouches count]; i++) { UITouch *touch = allTouches[i]; for (int j=0; j<MAX_TOUCHES; j++) { if (touch == savedTouches[j]) { touchInRect[j] = false; savedTouches[j] = NULL; break; } } } } - (CGRect)rectWithSize:(CGSize)size andCenter:(CGPoint)point { return CGRectMake(point.x - size.width/2,point.y - size.height/2,size.width,size.height); } @end 我将MAX_TOUCHES设置为4,因此屏幕上会有四个对象.这个的基本概念是在调用touchesBegan ::时将每个UITouch ID存储在savedTouches数组中,然后在touchesMoved :: called时将每个ID与屏幕上的触摸进行比较. 只需将代码粘贴到.m文件中即可.示例结果如下所示: 希望这可以帮助 :) (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |