应用内添加指纹识别

iOS8之后苹果发布了指纹识别的功能，通过touch ID来识别用户，做用户授权，主要是依赖于LocalAuthentication库

指纹识别：一判断设备是否支持指纹识别功能

二识别指纹，成功后做相应的动作，失败后提醒用户指纹识别失败

先引入#import <LocalAuthentication/LocalAuthentication.h>

LAContext *context = [[LAContext alloc] init];
    NSError *error = nil;
    //验证是否支持指纹识别
    if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {
        NSLog(@"支持指纹识别的应用");
        //验证身份
        [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:NSLocalizedString(@"需要指纹来验证你的身份", @"hello") reply:^(BOOL success, NSError *error) {
            if (success) {
                NSLog(@"成功");
            } else {
                switch (error.code) {
                    case LAErrorUserCancel:
                        NSLog(@"用户取消了授权 - %@", error.localizedDescription);
                        break;
                    case LAErrorUserFallback:
                        NSLog(@"用户点击了“输入密码”按钮 - %@", error.localizedDescription);
                        break;
                    case LAErrorAuthenticationFailed:
                        NSLog(@"您已授权失败3次 - %@", error.localizedDescription);
                        break;
                    case LAErrorTouchIDLockout:
                        NSLog(@"指纹被锁定 - %@", error.localizedDescription);
                        break;
                    case LAErrorSystemCancel:
                        NSLog(@"应用程序进入后台 - %@", error.localizedDescription);
                        break;
                    default:
                        NSLog(@"++%@--%zd", error.localizedDescription, error.code);
                        break;
                }
            }
        }];
    } else {
        switch (error.code) {
            case LAErrorPasscodeNotSet:
                NSLog(@"未设置密码 - %@", error.localizedDescription);
                break;
            case LAErrorTouchIDNotEnrolled:
                NSLog(@"未注册 Touch ID - %@", error.localizedDescription);
                break;
            case kLAErrorTouchIDNotAvailable:
                NSLog(@"该设备不支持 Touch ID - %@", error.localizedDescription);
                break;
            default:
                NSLog(@"--%@--%zd", error.localizedDescription, error.code);
                break;
        }
    }