iphone - Drag and drop objects and return them to their original position -

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i'm trying drag image , let return it's original position after releasing it. far, can drag image creating button using following code: (as seen in answer question: basic drag , drop in ios ) 

uibutton *button = [uibutton buttonwithtype:uibuttontypecustom]; [button addtarget:self action:@selector(imagetouch:withevent:) forcontrolevents:uicontroleventtouchdown]; [button addtarget:self action:@selector(imagemoved:withevent:) forcontrolevents:uicontroleventtouchdraginside]; [button setimage:[uiimage imagenamed:@"vehicle.png"] forstate:uicontrolstatenormal]; [self.view addsubview:button];

and later define: 

- (ibaction) imagemoved:(id) sender withevent:(uievent *) event {     cgpoint point = [[[event alltouches] anyobject] locationinview:self.view];     uicontrol *control = sender;     control.center = point; }

how can make return it's original position after releasing ?, starters save position @ each image supposed return, then, there anyway indicate uiimage go it's current position , move 1 ?, or other alterative solution ?

you know what, working on yesterday, here go little bonus animation:

- (void)previewimagetouchupinside:(uibutton*)abutton {     if (!previewimagedragged) {         [self selectpreviewimage:abutton];         return; }      previewimagedragged = no;      // if user drag photo little , release, we'll still treat tap     //  instead of drag     if ((originalpositionofbutton.x - abutton.center.x) *        (originalpositionofbutton.x - abutton.center.x) +        (originalpositionofbutton.y - abutton.center.y) *        (originalpositionofbutton.y - abutton.center.y) < 10) {         abutton.center = originalpositionofbutton;         [self selectpreviewimage:abutton];         return;     }      [uiview animatewithduration:0.5         delay:0         options:uiviewanimationoptioncurveeaseout |         uiviewanimationoptionallowuserinteraction animations:^{         abutton.center = originalpositionofbutton;     } completion:nil]; }    - (void)previewimagedraggedinside:(uibutton*)abutton event:(uievent*)event {     if (!previewimagedragged) {         originalpositionofbutton = abutton.center;         [self.view bringsubviewtofront:abutton];         [self.view bringsubviewtofront:[self.view viewwithtag:choose_photo_button_tag]];     }      uitouch* touch = [[event alltouches] anyobject];      previewimagedragged = yes;     abutton.center = cgpointmake(abutton.center.x+[touch locationinview:self.view].x-         [touch previouslocationinview:self.view].x,          abutton.center.y+[touch locationinview:self.view].y-         [touch previouslocationinview:self.view].y); }

it still has few magic numbers , haven't renamed functions , variables suit example, should clear. did indentation here since don't manually break long lines in code.


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