ObjC iOS11：成为第一个响应者在inputAccessoryView当文本字段不露面

Question

所以我有这样的代码来创建我inputAccessoryView当键盘显示出来：

self.toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 1024, 44)];; 
self.toolbar.backgroundColor = [UIColor blueColor]; 

NSMutableArray *toolbarItems = [[NSMutableArray alloc] init]; 

UILabel *nrLabel = [[UILabel alloc] initWithFrame:CGRectMake(7, 3, 140, 21)]; 
nrLabel.text = @"Number:"; 
[toolbarItems addObject:[[UIBarButtonItem alloc] initWithCustomView:nrLabel]]; 

self.nrTextField = [[UITextField alloc] initWithFrame:CGRectMake(8, 8, 140, 28)]; 
self.nrTextField.backgroundColor = [UIColor whiteColor]; 
[toolbarItems addObject:[[UIBarButtonItem alloc] initWithCustomView:self.nrTextField]]; 

UILabel *amountLabel = [[UILabel alloc] initWithFrame:CGRectMake(7, 3, 100, 21)]; 
amountLabel.text = @"Amount:"; 
[toolbarItems addObject:[[UIBarButtonItem alloc] initWithCustomView:amountLabel]]; 

self.amountTextField = [[UITextField alloc] initWithFrame:CGRectMake(8, 8, 100, 28)]; 
self.amountTextField.backgroundColor = [UIColor whiteColor]; 
[toolbarItems addObject:[[UIBarButtonItem alloc] initWithCustomView:self.amountTextField]]; 

self.toolbar.items = toolbarItems; 
self.toolbar.autoresizingMask = UIViewAutoresizingFlexibleWidth; 

[self.nrTextField becomeFirstResponder]; 
return self.toolbar; 

它，只要我不工作正常告诉nrTextField成为第一响应者。这是不合法的吗？

Answer 1

由于这个UIToolbar应该是键盘的扩展，我不得不在正确的时间调用becomeFirstResponder。 所以我写了一个keyboardDidShow方法，并通过NSNotification调用它。在这种方法中，我将TextField设置为第一响应者。