1 #import "AppDelegate.h"
2
3 @interface AppDelegate ()<UITextFieldDelegate>// 添加代理协议
4
5 @end
6
7 @implementation AppDelegate
8
9
10 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
11 self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
12 // Override point for customization after application launch.
13 self.window.backgroundColor = [UIColor whiteColor];
14
15
16 UITextField *tf = [[UITextField alloc] initWithFrame:CGRectMake(60, 100, 180, 30)];
17 //确认代理
18 tf.delegate = self;
19 tf.keyboardType = UIKeyboardAppearanceDefault;
20
21 tf.backgroundColor = [UIColor greenColor];
22 [self.window addSubview:tf];
23
24 [self.window makeKeyAndVisible];
25 return YES;
26 }
27
28 - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
29 {
30 int length = [textField.text length];
31 // 2代表*号的起始位置,9代表*号的结束位置
32 if (length > 2 && length < 9) {
33 NSMutableString *text = [textField.text mutableCopy];
34 [text replaceCharactersInRange:NSMakeRange(length - 1 , 1) withString:@"*"];
35 textField.text = text;
36 }
37 return YES;
38 }
39
40 @end
实现的效果如下图：
