摘要。基于某些benchmarks,我为我的iPhone JSON解析器选择了yajl-objc。我用一个任意的自定义类(一个NSNumber和两个NSString属性)测试它。如果我创建了一个带有与类属性匹配的键值对的NSDictionary,我可以使用[dictionary yajl_JSON]
对字典进行编码。当我尝试用[custom yajl_JSON]
直接编码自定义类的实例时,我得到了这个编译器错误:
Terminating app due to uncaught exception 'YAJLParsingUnsupportedException', reason: 'Object of type (Custom) must implement dataUsingEncoding: to be parsed'
。
即使我实施- (id)JSON
(如yajl-objc readme中所述),我也收到了错误消息。我知道我的代码,而不是库,是问题所在。我无法弄清楚我做错了什么。
详细信息。我的Custom.h:
#import
@interface Custom : NSObject {
NSString *name;
NSNumber *number;
NSString *text;
}
@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSNumber *number;
@property (nonatomic, copy) NSString *text;
@end
在Custom.m中,我根据yajl-obj文档定义了- (id)JSON
方法:
- (id)JSON
{
NSDictionary *jsonDictionary =
[[[NSMutableDictionary alloc] init] autorelease];
[jsonDictionary setValue:name forKey:@"name"];
[jsonDictionary setValue:number forKey:@"number"];
[jsonDictionary setValue:text forKey:@"text"];
return jsonDictionary;
}
创建一个键值匹配字典并对其进行编码可以正常工作:
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
[dict setValue:self.custom.name forKey:@"name"];
[dict setValue:self.custom.number forKey:@"number"];
[dict setValue:self.custom.text forKey:@"text"];
NSString *JSONString = [dict yajl_JSON];
但是当我打电话给NSString* JSONString = [custom yajl_JSON]
时;这是我得到的编译器错误和堆栈跟踪:
*** Terminating app due to uncaught exception 'YAJLParsingUnsupportedException', reason: 'Object of type (Custom) must implement dataUsingEncoding: to be parsed'
*** Call stack at first throw:
(
0 CoreFoundation 0x0266bb99 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x027bb40e objc_exception_throw + 47
2 CoreFoundation 0x02624238 +[NSException raise:format:arguments:] + 136
3 CoreFoundation 0x026241aa +[NSException raise:format:] + 58
4 TestCustomFileFormat 0x00005151 -[NSObject(YAJL) yajl_JSONWithOptions:error:] + 206
5 TestCustomFileFormat 0x00005212 -[NSObject(YAJL) yajl_JSON:] + 49
6 TestCustomFileFormat 0x00005249 -[NSObject(YAJL) yajl_JSON] + 49
7 TestCustomFileFormat 0x00002eba -[TestViewController loadInstruction] + 758
8 TestCustomFileFormat 0x00002aa5 -[TestViewController viewDidLoad] + 77
9 UIKit 0x0037585a -[UIViewController view] + 179
10 TestCustomFileFormat 0x00002377 -[TestCustomFileFormatAppDelegate application:didFinishLaunchingWithOptions:] + 112
11 UIKit 0x002cc6a7 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1163
12 UIKit 0x002ceb30 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 346
13 UIKit 0x002d8b6c -[UIApplication handleEvent:withNewEvent:] + 1958
14 UIKit 0x002d12bc -[UIApplication sendEvent:] + 71
15 UIKit 0x002d613f _UIApplicationHandleEvent + 7672
16 GraphicsServices 0x02f4b81e PurpleEventCallback + 1578
17 CoreFoundation 0x0264cff4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
18 CoreFoundation 0x025ad807 __CFRunLoopDoSource1 + 215
19 CoreFoundation 0x025aaa93 __CFRunLoopRun + 979
20 CoreFoundation 0x025aa350 CFRunLoopRunSpecific + 208
21 CoreFoundation 0x025aa271 CFRunLoopRunInMode + 97
22 UIKit 0x002ce3ed -[UIApplication _run] + 625
23 UIKit 0x002da272 UIApplicationMain + 1160
24 TestCustomFileFormat 0x000022e4 main + 102
25 TestCustomFileFormat 0x00002275 start + 53
)
terminate called after throwing an instance of 'NSException'
作为回应,我尝试遵循NSCoding,使用NSKeyedArchiver创建类实例的NSMutableData表示并调用[data yajl_JSON]
,但这也不起作用。
我知道我错过了一些简单的事情,但我太愚蠢了,无法弄明白。
答案 0 :(得分:1)
你做错了。要从对象创建JSON字符串,请使用yajl_JSONString
。 yail_JSON
用于获取字符串(或NSData
对象或可以存档的内容)并将其解析为对象。