object-c 的异常构造，并抛出

    @try {        NSException *exception = [NSException exceptionWithName: @"HotTeaException"                                                         reason: @"The tea is too hot"                                                       userInfo: nil];        @throw exception;    }    @catch (NSException *exception) {        NSLog(@"main: Caught %@: %@", [exception name], [exception reason]);    }    @finally {        NSLog(@"finally");    }