如何将 NSDictionary 元素转换为 NSData （dataUsingEncoding 导致崩溃）

Question

我尝试将 NSDictionary 元素转换为 NSData 元素：

...    
while ((key = [enumerator nextObject])) 
    {
        NSString *temp = [dictionary objectForKey:key];
        if ([key isEqualToString:@"results"]) 
        {
            //Crash HERE! -------------------------->>>>
            NSData *myData2 = [temp dataUsingEncoding:NSUTF32BigEndianStringEncoding];

            NSDictionary *dictionary2 = [[CJSONDeserializer deserializer] deserializeAsDictionary:myData2 error:&error];
            NSLog(@"Error: %@",error);
            //print dictionary
            NSEnumerator *enumerator2 = [dictionary2 keyEnumerator];
            id key2;
            while (key2 = [enumerator2 nextObject]) 
            {
                NSLog(@"Chiave: %@ | valore: %@",key2,[dictionary objectForKey:key2] );
            }

        }
    }
...

但这样会崩溃：

    -[__NSArrayI dataUsingEncoding:]: unrecognized selector sent to instance 0x5b1c590
    Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayI dataUsingEncoding:]: unrecognized selector sent to instance 0x5b1c590'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x025fe919 __exceptionPreprocess + 185
    1   libobjc.A.dylib                     0x0274c5de objc_exception_throw + 47
    2   CoreFoundation                      0x0260042b -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
    3   CoreFoundation                      0x02570116 ___forwarding___ + 966
    4   CoreFoundation                      0x0256fcd2 _CF_forwarding_prep_0 + 50
    5   taxi rider                          0x00002722 -[taxi_riderViewController viewDidLoad] + 1508
    6   UIKit                               0x00375c26 -[UIViewController view] + 179
    7   taxi rider                          0x00001f61 -[taxi_riderAppDelegate application:didFinishLaunchingWithOptions:] + 74
    8   UIKit                               0x002ce543 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1163
    9   UIKit                               0x002d09a1 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 346
    10  UIKit                               0x002da452 -[UIApplication handleEvent:withNewEvent:] + 1958
    11  UIKit                               0x002d3074 -[UIApplication sendEvent:] + 71
    12  UIKit                               0x002d7ac4 _UIApplicationHandleEvent + 7495
    13  GraphicsServices                    0x02c78afa PurpleEventCallback + 1578
    14  CoreFoundation                      0x025dfdc4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
    15  CoreFoundation                      0x02540737 __CFRunLoopDoSource1 + 215
    16  CoreFoundation                      0x0253d9c3 __CFRunLoopRun + 979
    17  CoreFoundation                      0x0253d280 CFRunLoopRunSpecific + 208
    18  CoreFoundation                      0x0253d1a1 CFRunLoopRunInMode + 97
    19  UIKit                               0x002d0226 -[UIApplication _run] + 625
    20  UIKit                               0x002dbb58 UIApplicationMain + 1160
    21  taxi rider                          0x00001ef4 main + 102
    22  taxi rider                          0x00001e85 start + 53
)
terminate called after throwing an instance of 'NSException'

有人有想法吗？

Answer 1

-dataUsingEncoding: 是一个 NSString 方法。

根据错误消息，您发送到的对象不是 NSString，而是 NSArray。

如果您尝试将 NSArray 转换为 NSData，请参阅 如何将 NSArray 转换为 NSData？

或者，因为看起来您希望能够使用 [CJSONDeserializer deserializer]< 读取 NSData 对象/code>，您可能应该使用与它相反的任何内容来创建它（该包中有一个 CJSONSerializer 类吗？）。