获取extension，判断第一次

keyBoard/ViewController.m

@@ -8,22 +8,29 @@
 #import "ViewController.h"
 
 @interface ViewController ()
-@property (nonatomic,strong)UITextField *textField;
+@property (nonatomic, strong) UITextView *textView;
 @end
 
 @implementation ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
-    // Do any additional setup after loading the view.
-    self.view.backgroundColor = [UIColor grayColor];
-    self.textField = [[UITextField alloc] init];
-    self.textField.frame = CGRectMake(100, 100, 200, 40);
-    self.textField.layer.borderWidth = 1;
-    self.textField.layer.borderColor = [UIColor redColor].CGColor;
-    [self.view addSubview:self.textField];
-    
+    [self setupTextField];
+}
 
+- (void)setupTextField {
+    CGRect frame = CGRectMake(([UIScreen mainScreen].bounds.size.width - 200)/2, ([UIScreen mainScreen].bounds.size.height - 200)/2, 200, 200);
+    self.textView = [[UITextView alloc] initWithFrame:frame];
+    self.textView.text = @"测试";
+    self.textView.layer.borderColor = [UIColor blackColor].CGColor;
+    self.textView.layer.borderWidth = 0.5;
+    [self.view addSubview:self.textView];
+    
+    [self.textView becomeFirstResponder];
+}
+
+- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
+    [self.textView resignFirstResponder];
 }