iOS pop動畫之衰減動畫的基本使用

衰減動畫

- (void)viewdidload {

[super viewdidload];

[self initcirclebtn];

- (void)initcirclebtn {

// 例項化手勢，並最終將手勢新增到圓形按鈕上

uipangesturerecognizer *pan = [[uipangesturerecognizer alloc]initwithtarget:self action:@selector(handlepan:)];

// 例項化圓形按鈕

uibutton *circlebtn = [[uibutton alloc]init];

circlebtn.bounds = cgrectmake(0, 0, 100, 100);

circlebtn.center = self.view.center;

circlebtn.backgroundcolor = [uicolor redcolor];

circlebtn.layer.cornerradius = cgrectgetwidth(circlebtn.frame) / 2;

[circlebtn addgesturerecognizer:pan];

[circlebtn addtarget:self action:@selector(handledown:) forcontrolevents:uicontroleventtouchdown];

[self.view addsubview:circlebtn];

- (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:cgpointmake(0, 0) inview:self.view];// 這句比較重要，因為handlepan:會持續呼叫，如果不把上一次呼叫該方法產生的位移清零，按鈕會移動得很快

// 鬆手時，啟動衰減動畫

if (recognizer.state == uigesturerecognizerstateended) {

cgpoint velocity = [recognizer velocityinview:self.view]; // 獲取鬆手時，手勢在控制器view的速度

popdecayanimation *popanimation = [popdecayanimation animationwithpropertynamed:kpoplayerposition]; // 例項化衰減動畫，該衰減動畫作用於position

[popanimation setvelocity:[nsvalue valuewithcgpoint:velocity]]; // 設定衰減動畫的初始速度

[recognizer.view pop_addanimation:popanimation forkey:@"suibian"];// 新增衰減動畫到圓形按鈕