objective c - iOS UIButton disappears after setting background image to nil -

i have uibutton has no title or initial background image. when pressed, button background image changes , when pressed again, set nil. ios 6.x, button disappears. here code:

- (ibaction)resetall: (id) sender { [self reset];  (uiview *view in self.view.subviews) {      if ([[[view class] description] isequaltostring:@"uiroundedrectbutton"]) {         uibutton *thebutton = (uibutton *)view;                   int ntag = thebutton.tag;          switch (ntag) {             case 11: {                 thebutton.tag = 10;                 [thebutton setbackgroundimage:nil forstate:uicontrolstatenormal];                 break;             }             case 21: {                 thebutton.tag = 20;                 [thebutton setbackgroundimage:nil forstate:uicontrolstatenormal];                 [thebutton setenabled:yes];                 break;             }             case 31: {                 thebutton.tag = 30;                 [thebutton setbackgroundimage:nil forstate:uicontrolstatenormal];                 [thebutton setenabled:yes];                 break;             }             case 41: {                 thebutton.tag = 40;                 [thebutton setbackgroundimage:nil forstate:uicontrolstatenormal];                 [thebutton setenabled:yes];                 break;             }             case 51: {                 thebutton.tag = 50;                 [thebutton setbackgroundimage:nil forstate:uicontrolstatenormal];                 [thebutton setenabled:yes];                 break;             }         }     } } return; 

this code works fine:

- (ibaction)buttonclicked: (id) sender { uibutton *btn = (uibutton *)sender;  // current tag value int currenttag = [sender tag];  // toggle check buttons if (currenttag == 10 || currenttag == 20 || currenttag == 30 || currenttag == 40 || currenttag == 50) {         [btn setbackgroundimage:[uiimage imagenamed:@"check.png"] forstate:uicontrolstatenormal];         btn.tag = ++currenttag; }  else     if (currenttag == 11 || currenttag == 21 || currenttag == 31 || currenttag == 41 || currenttag == 51) {         [btn setbackgroundimage:nil forstate:uicontrolstatenormal];         btn.tag = --currenttag; }  [self calculate]; 

any suggestions or appreciated!

instead of changing background image of button in uicontrolstatenormal, why not instead change states of button? if created button programmatically, need add line

[btn setbackgroundimage:[uiimage imagenamed:@"check.png"] forstate:uicontrolstateselected]; 

then, when pressed , want arrow image:

[btn setselected:yes]; 

and set default appearance:

[btn setselected:no]; 

if made button in xib, can set state images changing state config selected , set image there.