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我有一个采用 NSDictionary 的方法： 

-(id)initWithJSONDictionary:(NSDictionary *)dataDictionary{
     self = [super init];
     NSLog(@"********************************* %@ ",dataDictionary);
     for(NSString * key in dataDictionary){
         if([key isEqualToString:@"filters"]){
             NSDictionary * filtersSubDict = [dataDictionary objectForKey:key];
             for(NSString *sfKey in filtersSubDict){
                 NSLog(@"new filter: %@", sfKey );               
                 NSDictionary *filterObject = [filtersSubDict objectForKey:sfKey];
                 // this line is throwing some kind of thread exception
             }
          }
      }
      return self;
}

关于为什么带有注释的行抛出异常的任何线索：**首先抛出调用堆栈：

(0x1d04012 0x1141e7e 0x1d8f4bd 0x1cf3bbc 0x1cf394e 0x1052b 0x137fe 0x259b3 0x4a6853f 0x4a7a014 0x4a6a7d5 0x1caaaf5 0x1ca9f44 0x1ca9e1b 0x1c5e7e3 0x1c5e668 0x85ffc 0x27fd 0x2725)
libc++abi.dylib: terminate called throwing an exception
(lldb)

显示整个 NSDictionary 的第一个 NSLog 显示了这一点：

{
    errorCode = 0;
    filters =     (
                {
            id = 1001;
            name = "Base Lenses";
            sequence = 1;
        },
                {
            id = 1002;
            name = "Standard Anti-Reflective";
            sequence = 2;
        },
                {
            id = 1003;
            name = "Premium Anti-Reflective";
            sequence = 3;
        },
                {
            id = 1004;
            name = "Enhanced Scratch Resistance";
            sequence = 4;
        },
                {
            id = 1005;
            name = Sun;
            sequence = 5;
        },
                {
            id = 1006;
            name = Tint;
            sequence = 6;
        },
                {
            id = 1007;
            name = "Clear To Dark";
            sequence = 7;
        }
    );
    lenses =     {
        Glass =         (
                        {
                fsv = 1;
                inStore = 1;
                lom = 0;
                price = 465;
                style = "Glass Std AR";
                styleFilters =                 (
                    1002
                );
                type = "Single Vision";
                visionCorrection = singleVision;
            },
                        {
                fsv = 1;
                inStore = 0;
                lom = 1;
                price = 395;
                style = "Prem Plastic Std AR";
                styleFilters =                 (
                    1002
                );
                type = "SV HD";
                visionCorrection = singleVision;
            }
        );
        "Plastic/Hi-index" =         (
                        {
                fsv = 1;
                inStore = 1;
                lom = 0;
                price = 395;
                style = "Prem Plastic Std AR";
                styleFilters =                 (
                    1002,
                    1006
                );
                type = "SV HD";
                visionCorrection = singleVision;
            },
                        {
                fsv = 1;
                inStore = 0;
                lom = 1;
                price = 465;
                style = "Glass Std AR";
                styleFilters =                 (
                    1002,
                    1006
                );
                type = "SV HD";
                visionCorrection = singleVision;
            }
        );
        Polycarbonate =         (
                        {
                fsv = 1;
                inStore = 1;
                lom = 0;
                price = 395;
                style = "FeatherWates Classic";
                styleFilters =                 (
                    1001
                );
                type = "SV Wrap";
                visionCorrection = singleVision;
            },
                        {
                fsv = 1;
                inStore = 0;
                lom = 1;
                price = 495;
                style = "FeatherWates Classic";
                styleFilters =                 (
                    1001
                );
                type = "SV Wrap";
                visionCorrection = singleVision;
            }
        );
    };
    materials =     (
        Polycarbonate,
        "Plastic/Hi-index",
        Glass
    );
}

我正在尝试为“过滤器”中的每个节点创建一个新对象，以获取 id、名称和序列值

4

1 回答 1

4

在没有看到您的NSLog语句在说什么或不知道您的异常实际上是什么的情况下，这里所有可能在您的代码中引发异常的事情：

for(NSString *key in dataDictionary) {

如果dataDictionary它实际上不是一个NSDictionary, 而是其他一些非<NSFastEnumeration>JSON 对象，比如一个NSString,NSNumber等，则这条线可能会抛出。

    if([key isEqualToString:@"filters"]){

key如果实际上不是 anNSString并因此没有实现 method ，则此行可能会抛出-isEqualToString:。

        NSDictionary *filtersSubDict = [dataDictionary objectForKey:key];

如果dataDictionary是一个可快速枚举的 JSON 对象，但实际上不是一个NSDictionary. （换句话说，它可能是一个NSArray，并且这一行会抛出一个“不识别选择器'objectForKey：'”异常）。

        for (NSString *sfKey in filtersSubDict) {

像上面一样，这可能会抛出 if filtersSubDictis not anNSArray或 an NSDictionary。

            NSLog(@"new filter: %@", sfKey );
            NSDictionary *filterObject = [filtersSubDict objectForKey:sfKey];

这可能会抛出 if filtersSubDictis not an NSDictionarybut is an NSArray（同上）。

        }
    }
}

因此，如果它在线上抛出filterObject = ...，那么很可能这filtersSubDict实际上不是字典，并且您会得到一个无法识别的选择器异常。

于 2013-04-09T18:04:48.930 回答