在iOS中未实现谓词的SQL生成

Question

我在核心数据中得到以下错误

 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unimplemented SQL generation for predicate (mRemainderId LIKE <MSaveRemainders: 0x1740cae90>

下面是我使用的代码

  -(void) deleteRemainders:(NSMutableArray*) deleteArray{
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"MSaveRemainders" inManagedObjectContext:self.managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    for (NSString *remainderId in deleteArray) {
        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"mRemainderId LIKE %@", remainderId];
        [fetchRequest setEntity:entity];
        [fetchRequest setPredicate:predicate];
        [fetchRequest setReturnsObjectsAsFaults:NO];
        NSError *error;
        NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
        for (NSManagedObject *managedObject in fetchedObjects) {
            [self.managedObjectContext deleteObject:managedObject];
        }
    }

}

删除数组

(实体: MSaveRemainders；id: 0xd000000000040002；数据：{ furtherSubCategoryId =零；mDate = "2016-05-10"；mNote =“金融”；mNumberOfGlasses = 6；mRemainderId = 1462793810；mRepeat =无；mRepeatDays = ""；mSleepTime =“上午10:00”；mSnooze =不；mTime = "(\n 05:06 pm\n)“；mTitle =金融；mTone =”06: AM"；mWaterInLitres = "1.6"；mYourWeight = 50；mainCategoryId = 1；subCategoryId = "(null)"；})

Answer 1

因为您试图在不包含NSString的数组中访问NSString，所以您的数组只包含MSaveRemainders，因此您应该获得类MSaveRemainders的对象并检查它的属性，所以您的方法应该如下所示

-(void) deleteRemainders:(NSMutableArray*) deleteArray{
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"MSaveRemainders" inManagedObjectContext:self.managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    for (MSaveRemainders *savedReminder in deleteArray) {
        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"mRemainderId LIKE %@", [savedReminder.data valueForKey:@"mRemainderId"]];

        // or like the follwing if "data" is a property of a class ( model )
        /*
         NSPredicate *predicate = [NSPredicate predicateWithFormat:@"mRemainderId LIKE %@", savedReminder.data.mRemainderId ];

         */
        [fetchRequest setEntity:entity];
        [fetchRequest setPredicate:predicate];
        [fetchRequest setReturnsObjectsAsFaults:NO];
        NSError *error;
        NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
        for (NSManagedObject *managedObject in fetchedObjects) {
            [self.managedObjectContext deleteObject:managedObject];
        }
    }
}