RMErrorRecoveryAttempter 是一个遵守 NSErrorRecoveryAttempting 非正式协议的类，它利用块的功能，允许您为错误提供恢复选项。
阅读 Realmac 博客上的 Cocoa Error Handling and Recovery 博客文章，了解更多错误处理技巧。
示例项目，RMErrorRecoveryAttempterSampleProject，是一个 iOS 应用，可以创建锁定和解锁的项。如果您滑动删除一个锁定的项，将会创建一个错误。这个错误的用户信息字典中包含一个 RMErrorRecoveryAttempter 对象，该对象有两个恢复选项，每个选项都有一个标题和块对象。恢复选项的标题用于填充提醒框中按钮，当点击按钮时，对应的块对象将被执行。这些恢复选项返回 YES 或 NO，以通知调用者是否重新发送失败的原始消息。
RMErrorRecoveryAttempter *errorRecoveryAttempter = [[RMErrorRecoveryAttempter alloc] init];
[errorRecoveryAttempter addRecoveryOptionWithLocalizedTitle:NSLocalizedString(@"Don\u2019t Unlock", @"RMMasterViewController delete locked item error don't unlock recovery option") recoveryBlock:^ BOOL (void) {
// Do not attempt to recover from the error. Return NO to inform the caller that they should not resend the message that failed.
return NO;
}];
[errorRecoveryAttempter addRecoveryOptionWithLocalizedTitle:NSLocalizedString(@"Unlock & Delete", @"RMMasterViewController delete locked item error unlock & delete recovery option") recoveryBlock:^ BOOL (void) {
// Do the required work to recover from the error; unlock the item.
[item setLocked:NO];
// Return YES to inform the caller that they should resend the message that failed, not that the original functionality of that message has been performed.
return YES;
}];
/*
The `userInfo` dictionary populated with our localized title and messages strings and `RMErrorRecoveryAttempter`. If you have an underlying
error, for example an error from a failed `-[NSManagedObjectContext save:]`, you can include it under the `NSUnderlyingErrorKey`.
*/
NSDictionary *userInfo = @{
NSLocalizedDescriptionKey : NSLocalizedString(@"Cannot delete a locked item", @"RMMasterViewController delete locked item error description"),
NSLocalizedRecoverySuggestionErrorKey : NSLocalizedString(@"This item cannot be deleted because it is currently locked. Would you like to Unlock & Delete this item?", @"RMMasterViewController delete locked item error recovery suggestion"),
NSRecoveryAttempterErrorKey : errorRecoveryAttempter,
NSLocalizedRecoveryOptionsErrorKey : [errorRecoveryAttempter recoveryOptions],
};
*errorRef = [NSError errorWithDomain:RMErrorRecoveryAttempterSampleProjectErrorDomain code:RMErrorRecoveryAttempterSampleProjectErrorCodeLockedItem userInfo:userInfo];
使用 UIResponder+RMErrorRecovery 类别来显示提醒框。如果完成处理器的 recovered 参数是 YES，则用户选择了恢复路径，因此重新发送删除项的消息。
- (void)rm_presentError:(NSError *)error completionHandler:(void (^)(BOOL recovered))completionHandler;
在 OS X 上，您可以使用以下两个 AppKit 方法来显示错误。
- (BOOL)presentError:(NSError *)error;
- (void)presentError:(NSError *)error modalForWindow:(NSWindow *)window delegate:(id)delegate didPresentSelector:(SEL)didPresentSelector contextInfo:(void *)contextInfo;
如果您的项目没有使用 ARC，您需要在 RMErrorRecoveryAttempter 和 UIResponder+RMErrorRecovery 源文件上设置 -fobjc-arc 编译器标志。要在 Xcode 中设置这些，请转到您的活动目标并选择“构建阶段”选项卡。展开“编译源代码”部分，选择提到的源文件，按 Enter，然后插入 -fobjc-arc。
有关此项目，请联系 James Beith，[email protected]
Keith Duncan, @keith_duncan
Damien DeVille, @DamienDeVille
James Beith, @jamesbeith
有关更多信息，请参阅 LICENSE 文件。