2
我遇到了一些问题,可能对您很简单。我正在使用核心数据。我有一个实体:Session,它有三个属性:access_token,user_id和secret。尝试访问特定对象属性时出现无法识别的选择器错误
Session.h:
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
@interface Session : NSManagedObject
@property (nonatomic) NSString * access_token;
@property (nonatomic) NSNumber * user_id;
@property (nonatomic) NSString * secret;
@end
Session.m:
#import "Session.h"
@implementation Session
@dynamic access_token;
@dynamic user_id;
@dynamic secret;
@end
有一个代码,其中IM使用该实体:
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
Session *newSession = [NSEntityDescription insertNewObjectForEntityForName:@"Session" inManagedObjectContext:managedObjectContext];
if (newSession != nil) {
NSLog(@"access_token: %@", [JSON objectForKey:@"access_token"]);
NSLog(@"user_id: %@", [JSON objectForKey:@"user_id"]);
NSLog(@"secret: %@", [JSON objectForKey:@"secret"]);
newSession.access_token = [JSON objectForKey:@"access_token"];
newSession.user_id = [JSON objectForKey:@"user_id"];
newSession.secret = [JSON objectForKey:@"secret"];
}
NSError *savingError = nil;
if ([managedObjectContext save:&savingError] == YES) {
NSLog(@"Session saved");
} else {
NSLog(@"Session not saved");
}
} failure:nil];
此代码破例:
newSession.secret = [JSON objectForKey:@"secret"];
MyProject[7678:bc03] -[Session setSecret:]: unrecognized selector sent to instance 0x4e572d0
这是的NSLog:
2012-03-25 15:17:33.987 MyProject[7730:bc03] access_token: <some_access_token>
2012-03-25 15:17:33.988 MyPriject[7730:bc03] user_id: <some_user_id>
2012-03-25 15:17:33.989 MyProject[7730:bc03] secret: <some_secret>
这是堆栈跟踪:
*** Call stack at first throw:
(
0 CoreFoundation 0x010625a9 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x013e6313 objc_exception_throw + 44
2 CoreFoundation 0x010640bb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x00fd3966 ___forwarding___ + 966
4 CoreFoundation 0x00fd3522 _CF_forwarding_prep_0 + 50
5 MyProject 0x00004c94 __42-[APIWrapper authWithLogin:andPassword:]_block_invoke_0 + 836
6 MyProject 0x0000d452 __74+[AFJSONRequestOperation JSONRequestOperationWithRequest:success:failure:]_block_invoke_0 + 146
7 MyProject 0x0000e229 __block_global_3 + 41
8 libdispatch_sim.dylib 0x014de289 _dispatch_call_block_and_release + 16
9 libdispatch_sim.dylib 0x014e1833 _dispatch_main_queue_callback_4CF + 312
10 CoreFoundation 0x00fa1589 __CFRunLoopRun + 2521
11 CoreFoundation 0x00fa0840 CFRunLoopRunSpecific + 208
12 CoreFoundation 0x00fa0761 CFRunLoopRunInMode + 97
13 GraphicsServices 0x0153a1c4 GSEventRunModal + 217
14 GraphicsServices 0x0153a289 GSEventRun + 115
15 UIKit 0x000ebc93 UIApplicationMain + 1160
16 MyProject 0x0001b305 main + 181
17 MyProject 0x000020d5 start + 53
)
我真的不明白这里有什么问题。
This Works!问题出在'@dynamic',它是由Xcode生成的,而不是由'@synthesize'生成的。 – AntonPalich 2012-03-25 11:52:02
这是非常危险的错误。盲目地从@ dynamic切换到@ synthesize将导致这些方法被添加到类中。 @ dynamic是Objective C向编译器保证消息将在运行时处理的方式。这种方法不存在的保证; NSManagedObject的getter和setter的底层实现使用setValue:forKey:,而不是一个特定的方法。使用@ synthesize而不是@ dynamic将最有可能解决您的崩溃问题,但它会破坏CoreData。 – paulrehkugler 2013-11-27 03:56:33