IOS数字键盘左下角添加完成按钮的实现方法

- (void)addDoneButtonToNumPadKeyboard {   UIButton *doneButton = [UIButton buttonWithType:UIButtonTypeCustom];   if (systemVersion < 8.0){     doneButton.frame = CGRectMake(0, 163, 106, 53);   }else{     doneButton.frame = CGRectMake(0, SCREEN_SIZE.height-53, 106, 53);   }   doneButton.tag = NUM_PAD_DONE_BUTTON_TAG;   doneButton.adjustsImageWhenHighlighted = NO;   [doneButton setTitle:@"完成" forState:UIControlStateNormal];   [doneButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];   [doneButton addTarget:self action:@selector(doneButton:) forControlEvents:UIControlEventTouchUpInside];      NSArray *windowArr = [[UIApplication sharedApplication] windows];   if (windowArr != nil && windowArr.count > 1){     UIWindow *needWindow = [windowArr objectAtIndex:1];     UIView *keyboard;     for(int i = 0; i < [needWindow.subviews count]; i++) {       keyboard = [needWindow.subviews objectAtIndex:i];       NSLog(@"%@", [keyboard description]);       if(([[keyboard description] hasPrefix:@"<UIPeripheralHostView"] == YES) || ([[keyboard description] hasPrefix:@"<UIKeyboard"] == YES) || ([[keyboard description] hasPrefix:@"<UIInputSetContainerView"] == YES)){                  UIView *doneButtonView = [keyboard viewWithTag:NUM_PAD_DONE_BUTTON_TAG];         if (doneButtonView == nil){           [keyboard addSubview:doneButton];         }       }     }   } }  -(void)removeDoneButtonFromNumPadKeyboard {   UIView *doneButton = nil;    NSArray *windowArr = [[UIApplication sharedApplication] windows];   if (windowArr != nil && windowArr.count > 1){     UIWindow *needWindow = [windowArr objectAtIndex:1];     UIView *keyboard;     for(int i = 0; i < [needWindow.subviews count]; i++) {       keyboard = [needWindow.subviews objectAtIndex:i];       if(([[keyboard description] hasPrefix:@"<UIPeripheralHostView"] == YES) || ([[keyboard description] hasPrefix:@"<UIKeyboard"] == YES) || ([[keyboard description] hasPrefix:@"<UIInputSetContainerView"] == YES)){         doneButton = [keyboard viewWithTag:NUM_PAD_DONE_BUTTON_TAG];         if (doneButton != nil){           [doneButton removeFromSuperview];         }       }     }   } }