本文转载至 http://blog.csdn.net/jinkaiouyang/article/details/35555123

IOS8将指纹识别技术开放出来了。我们能够利用用户设置的touch ID来进行用户鉴权。

TouchID的API主要集成在LocalAuthentication.framework中。将改framework加入到工程中，并且需要iPhone5S和IOS8系统的支持，就能使用TouchID的API

了。

TouchID的API非常简单：

1、使用之前，需要先判断TouchID是否支持

[objc] view plaincopy

1. - (BOOL)canEvaluatePolicy:(LAPolicy)policy error:(NSError * __autoreleasing *)error;  

[objc] view plaincopy

1. - (void)evaluatePolicy:(LAPolicy)policy localizedReason:(NSString *)localizedReason reply:(void(^)(BOOL success, NSError *error))reply;  

[objc] view plaincopy

1. {  
2.     /// Device owner was authenticated using a biometric method. Biometrics (Touch ID) is required.  
3.     /// If Touch ID is not enabled, policy evaluation fails.  
4.     LAPolicyDeviceOwnerAuthenticationWithBiometrics = kLAPolicyDeviceOwnerAuthenticationWithBiometrics  
5. } NS_ENUM_AVAILABLE(10_10, 8_0);  

localizedReason

(void(^)(BOOL success,NSError *error))

示例代码：

[objc] view plaincopy

1. LAContext *context = [[LAContext alloc] init];  
2. NSError *contextError = nil;  
3. NSString *localizedReasonString = @"Need Authorize";  
4.   
5. if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&contextError]) {  
6.     [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics  
7.             localizedReason:localizedReasonString  
8.                       reply:^(BOOL success, NSError *error) {  
9.                           NSString *title, *message;  
10.                             
11.                           if (success) {  
12.                               title = @"Authorize Success";  
13.                               message = nil;  
14.                           } else {  
15.                               title = @"Authorize Faied";  
16.                               message = error.localizedFailureReason;  
17.                           }  
18.                             
19.                           UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title  
20.                                                                               message:message  
21.                                                                              delegate:nil  
22.                                                                     cancelButtonTitle:@"OK"  
23.                                                                     otherButtonTitles:nil];  
24.                           [alertView show];  
25.                       }];  
26. } else {  
27.     UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Context Error"  
28.                                                         message:contextError.localizedFailureReason  
29.                                                        delegate:nil  
30.                                               cancelButtonTitle:@"OK"  
31.                                               otherButtonTitles:nil];  
32.     [alertView show];