ViewController.m

@interface ViewController ()<UITextFieldDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UITextField * textField = [[UITextField alloc]initWithFrame:CGRectMake(100, 100, 100, 30)];
    textField.delegate = self;
    [textField setBackgroundColor:[UIColor redColor]];
    [self.view addSubview:textField];
    
}

// YES: 能输入 NO:不能输入
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    return NO;
}
- (BOOL)canPerformAction:(SEL)action withSender:(nullable id)sender
{
    return (action == @selector(paste:));
}

UITextField+Paste.m

@implementation UITextField (Paste)
- (void)paste:(UIMenuController *)menu
{
    // 将粘贴板的文字赋值给label
    self.text = [UIPasteboard generalPasteboard].string;
}