我的提取请求工作正常,我可以毫无问题地获取我提取的对象。我想做的是在实体不存在的情况下处理错误。问题是,我无法处理错误,因为当我调用 executeFetechRequest: error: 时应用程序崩溃,没有任何警告。
我的提取看起来像:
NSManagedObjectContext *context = [(AppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = [NSEntityDescription entityForName:@"Info" inManagedObjectContext:context];
request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"infoID" ascending:YES]];
[request setReturnsObjectsAsFaults:NO];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"infoID like %@",[a substringFromIndex:13]];
request.predicate = predicate;
request.fetchBatchSize = 1;
NSError *error = nil;
NSArray *results = [context executeFetchRequest:request error:&error];
if (error == nil) {
...
}
else {
//handle error
}
正如我所说,只要实体存在就没有问题,但如果它不存在,我想处理错误。任何想法?干杯
最佳答案
您可以询问模型是否存在这样的实体:
NSArray *entities = managedObjectModel.entities;
BOOL canExecute=NO;
for(NSEntityDescription *ed in entities) {
// check if entity name is equal to the one you are looking for
if(found) {
canExecute=YES;
break;
}
}
if(canExecute) {
// execute your request and all the rest...
} else {
NSLog(@"Entity description not found");
}
如果不存在则不执行获取请求
关于ios - 无法处理 executeFetchRequest 错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9522599/