基础知识
支持系统和机型
iOS系统的指纹识别功能最低支持的机型为iPhone 5s
,最低支持系统为iOS 8
,虽然安装iOS 7
系统的5s机型可以使用系统提供的指纹解锁功能,但由于API
并未开放,所以理论上第三方软件不可使用。
依赖框架
LocalAuthentication.framework
#import <LocalAuthentication/LocalAuthentication.h>
注意事项
做iOS 8
以下版本适配时,务必进行API验证,避免调用相关API引起崩溃。
使用类
LAContext
指纹验证操作对象
代码
- (void)authenticateUser
{
//初始化上下文对象
LAContext* context = [[LAContext alloc] init];
//错误对象
NSError* error = nil;
NSString* result = @"Authentication is needed to access your notes.";
//首先使用canEvaluatePolicy 判断设备支持状态
if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {
//支持指纹验证
[context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:result reply:^(BOOL success, NSError *error) {
if (success) {
//验证成功,主线程处理UI
}
else
{
NSLog(@"%@",error.localizedDescription);
switch (error.code) {
case LAErrorSystemCancel:
{
NSLog(@"Authentication was cancelled by the system");
//切换到其他APP,系统取消验证Touch ID
break;
}
case LAErrorUserCancel:
{
NSLog(@"Authentication was cancelled by the user");
//用户取消验证Touch ID
break;
}
case LAErrorUserFallback:
{
NSLog(@"User selected to enter custom password");
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
//用户选择输入密码,切换主线程处理
}];
break;
}
default:
{
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
//其他情况,切换主线程处理
}];
break;
}
}
}
}];
}
else
{
//不支持指纹识别,LOG出错误详情
switch (error.code) {
case LAErrorTouchIDNotEnrolled:
{
NSLog(@"TouchID is not enrolled");
break;
}
case LAErrorPasscodeNotSet:
{
NSLog(@"A passcode has not been set");
break;
}
default:
{
NSLog(@"TouchID not available");
break;
}
}
NSLog(@"%@",error.localizedDescription);
}
}
typedef NS_ENUM(NSInteger, LAError)
{
//授权失败
LAErrorAuthenticationFailed = kLAErrorAuthenticationFailed,
//用户取消Touch ID授权
LAErrorUserCancel = kLAErrorUserCancel,
//用户选择输入密码
LAErrorUserFallback = kLAErrorUserFallback,
//系统取消授权(例如其他APP切入)
LAErrorSystemCancel = kLAErrorSystemCancel,
//系统未设置密码
LAErrorPasscodeNotSet = kLAErrorPasscodeNotSet,
//设备Touch ID不可用,例如未打开
LAErrorTouchIDNotAvailable = kLAErrorTouchIDNotAvailable,
//设备Touch ID不可用,用户未录入
LAErrorTouchIDNotEnrolled = kLAErrorTouchIDNotEnrolled,
} NS_ENUM_AVAILABLE(10_10, 8_0);
操作流程
首先判断系统版本,iOS 8
及以上版本执行-(void)authenticateUser
方法,方法自动判断设备是否支持和开启Touch ID
。
iOS 9
感谢秋儿指出iOS 9加入了三种新的错误类型。
/// Authentication was not successful, because there were too many failed Touch ID attempts and
/// Touch ID is now locked. Passcode is required to unlock Touch ID, e.g. evaluating
/// LAPolicyDeviceOwnerAuthenticationWithBiometrics will ask for passcode as a prerequisite.
LAErrorTouchIDLockout NS_ENUM_AVAILABLE(10_11, 9_0) = kLAErrorTouchIDLockout,
/// Authentication was canceled by application (e.g. invalidate was called while
/// authentication was in progress).
LAErrorAppCancel NS_ENUM_AVAILABLE(10_11, 9_0) = kLAErrorAppCancel,
/// LAContext passed to this call has been previously invalidated.
LAErrorInvalidContext NS_ENUM_AVAILABLE(10_11, 9_0) = kLAErrorInvalidContext
其中,LAErrorTouchIDLockout
是在8.0中也会出现的情况,但并未归为单独的错误类型,这个错误出现,源自用户多次连续使用Touch ID失败,Touch ID被锁,需要用户输入密码解锁,这个错误的交互LocalAuthentication.framework
已经封装好了,不需要开发者关心。
LAErrorAppCancel
和LAErrorSystemCancel
相似,都是当前软件被挂起取消了授权,但是前者是用户不能控制的挂起,例如突然来了电话,电话应用进入前台,APP被挂起。后者是用户自己切到了别的应用,例如按home键挂起。
LAErrorInvalidContext
很好理解,就是授权过程中,LAContext对象被释放掉了,造成的授权失败。
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