Ios executefetchrequest导致崩溃
我正在尝试在iOS 7应用程序中实现核心数据(之前已经成功实现)。但是,当我执行executeFetchRequest方法时,应用程序崩溃。下面添加了最相关的代码:Ios executefetchrequest导致崩溃,ios,objective-c,core-data,executefetchrequest,Ios,Objective C,Core Data,Executefetchrequest,我正在尝试在iOS 7应用程序中实现核心数据(之前已经成功实现)。但是,当我执行executeFetchRequest方法时,应用程序崩溃。下面添加了最相关的代码: #import "JTHuntingSeasonDB.h" @implementation JTHuntingSeasonDB - (id)init { self = [super init]; if (self) { NSFileManager *fileManager = [NSFileMan
#import "JTHuntingSeasonDB.h"
@implementation JTHuntingSeasonDB
- (id)init {
self = [super init];
if (self) {
NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *documentsDirectory = [[fileManager URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] firstObject];
NSString *documentName = @"JTHuntingDB";
NSURL *url = [documentsDirectory URLByAppendingPathComponent:documentName];
document = [[UIManagedDocument alloc] initWithFileURL:url];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:[url path]];
if (fileExists) {
[document openWithCompletionHandler:^(BOOL success) {
if (success) {
NSLog(@"Document opened successfully");
self.allSpecies = [self getSpecies];
self.speciesToday = [self getSpeciesToday];
} else NSLog(@"Failed to open document");
}];
} else {
[document saveToURL:url forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
if (success) {
NSLog(@"Document created successfully");
self.allSpecies = [self getSpecies];
self.speciesToday = [self getSpeciesToday];
} else NSLog(@"Failed to create document, path: %@", url);
}];
}
}
return self;
}
#pragma mark - Core Data
- (NSArray *)getSpecies {
if (document.documentState == UIDocumentStateNormal) {
context = document.managedObjectContext;
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *country = [defaults stringForKey:@"Country"];
NSString *subregion = [defaults stringForKey:@"Subregion"];
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"HuntingDates"];
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES selector:@selector(localizedStandardCompare:)];
request.fetchBatchSize = 150;
request.fetchLimit = 150;
request.sortDescriptors = @[sortDescriptor];
if (subregion.length > 0) {
request.predicate = [NSPredicate predicateWithFormat:@"(country IN %@) AND (subregion IN %@)", country, subregion];
} else {
request.predicate = [NSPredicate predicateWithFormat:@"country IN %@", country];
}
NSError *error;
return [context executeFetchRequest:request error:&error];
}
return nil;
}
线路
return [context executeFetchRequest:request error:&error];
导致应用程序崩溃。这就是我迄今为止所做和发现的:
- 模拟器:删除应用程序并重置内容和设置
- Xcode:Clean(生成文件夹)
- “上下文”不是零
- NSLog打印出“文档创建/打开成功”
- 当应用程序崩溃时,控制台中只打印“lldb”
遵循Wain的建议后,我关闭了异常断点,得到了一条更具描述性的错误消息,指出谓词无效。通过将谓词中的IN替换为CONTAINS并更改变量“country”,使其不再返回nil,问题得以解决。我想这是您的谓词,因为
IN
是一个集合运算符,但您正在传递字符串(应该是数组/集合)
如果您使用的是字符串,那么应该在谓词中使用
CONTAINS
。假设CoreData持久存储存在于文档中,您将需要使用UIManagedDocument是否在异常发生时尝试继续以获取堆栈跟踪?我不知道核心数据,但至少会看到请求包含您期望的内容。除了Len,控制台和调试器回溯中还必须有更多内容。没有这一点就很难帮上忙。谢谢。按照上面注释中的建议删除异常断点,表明谓词无效。我将IN替换为CONTAINS,但我还发现谓词(country)中使用的变量是nil,这导致了崩溃。