在UITextField中能看到两个属性：
@property (readwrite, retain) UIView *inputView;
@property (readwrite, retain) UIView *inputAccessoryView;

在UITextField称为第一相应者的时候，会弹出系统默认的键盘，那么有时候并不想让系统默认弹出键盘，而是弹出自己自定义的view这种情况下就用到了UITextField这个控件的inputView属性了，我们可以自定义view，使其成为点击textfield默认弹出的自定义view。那么inputAccessoryView是什么呢，踏实键盘的辅助视图，机键盘上面那部分，同样当对inputAccessoryView设置了自定义的view时，键盘弹出的同时，该view会作为辅助视图出现在键盘上面，和键盘一块弹出，默然情况下，inputview在下，inputAccessoryView在上面。

@interface ViewController ()

@property (nonatomic, strong) UITextField *textField;
@property (nonatomic, strong) UIView *customInputView;
@property (nonatomic, strong) UIToolbar *customAccessoryView;

@property (nonatomic, strong) UISearchBar *searchBar;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self createUI];
}
- (void)createUI{
    [self.view addSubview:self.textField];
    self.textField.inputView = self.customInputView;
    self.textField.inputAccessoryView = self.customAccessoryView;
    
}
- (UITextField *)textField{
    if (!_textField) {
        _textField = [[UITextField alloc]initWithFrame:CGRectMake(50, 100, SCREEN_BOUNDS.size.width - 100, 30)];
        _textField.layer.borderWidth = 1.0;
        _textField.layer.borderColor = [UIColor lightGrayColor].CGColor;
        _textField.layer.cornerRadius = 4.0;
        _textField.placeholder = @"测试";
    }
    return _textField;
}

- (UIView *)customInputView{
    if (!_customInputView) {
        _customInputView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, SCREEN_BOUNDS.size.width, 261)];
        _customInputView.backgroundColor = [UIColor lightGrayColor];
        UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(0, 100, SCREEN_BOUNDS.size.width, 40)];
        label.textAlignment = NSTextAlignmentCenter;
        label.text = @"自定义inputView";
        [_customInputView addSubview:label];
//        _customInputView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_BOUNDS.size.width, 300)];
//        _customInputView.backgroundColor = [UIColor redColor];
        
    }
    return _customInputView;
}
- (UIToolbar *)customAccessoryView{
    if (!_customAccessoryView) {
        _customAccessoryView = [[UIToolbar alloc]initWithFrame:(CGRect){0,0,SCREEN_BOUNDS.size.width,40}];
        _customAccessoryView.barTintColor = [UIColor orangeColor];
        UIBarButtonItem *space = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
        UIBarButtonItem *finish = [[UIBarButtonItem alloc]initWithTitle:@"完成" style:UIBarButtonItemStyleDone target:self action:@selector(done)];
        [_customAccessoryView setItems:@[space,space,finish]];
    }
    return _customAccessoryView;
}

- (void)done{
    [self.textField resignFirstResponder];
}

运行结果如图所示：

自定义inputview和inputAccessoryView

这里不论改变_customInputView的高度，inputAccessoryView始终在inputView上面。
再看下面：

替换代码

其运行结果如图所示：

inputAccessoryView被inputview盖住情况

所以以后如果自定义UITextfield的inputview 那么千万不可吧pickview直接赋值给textfield的inputview否则会出现如图所示的bug。