我已经找到了这个问题的答案，似乎答案总是被遗忘了。但在我的情况下，没有那个。
每次调用某个Firebase方法时，我都会收到错误消息，但只有在某个＆＃39; if-else＆＃39;
之后才会收到消息错误顺便说一下，完整的信息：
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[0]'
*** First throw call stack:
(
0 CoreFoundation 0x0000000102dffe65 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x0000000102878deb objc_exception_throw + 48
2 CoreFoundation 0x0000000102d028ce -[__NSPlaceholderDictionary initWithObjects:forKeys:count:] + 318
3 CoreFoundation 0x0000000102d14c3b +[NSDictionary dictionaryWithObjects:forKeys:count:] + 59
4 libert2 0x0000000101757eb1 -[ViewController salvaridnofirebase] + 225
5 libert2 0x0000000101757b04 -[ViewController viewDidLoad] + 580
6 UIKit 0x000000010356af98 -[UIViewController loadViewIfRequired] + 1198
7 UIKit 0x000000010356b2e7 -[UIViewController view] + 27
8 UIKit 0x0000000103441ab0 -[UIWindow addRootViewControllerViewIfPossible] + 61
9 UIKit 0x0000000103442199 -[UIWindow _setHidden:forced:] + 282
10 UIKit 0x0000000103453c2e -[UIWindow makeKeyAndVisible] + 42
11 UIKit 0x00000001033cc663 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4131
12 UIKit 0x00000001033d2cc6 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1760
13 UIKit 0x00000001033cfe7b -[UIApplication workspaceDidEndTransaction:] + 188
14 FrontBoardServices 0x00000001061c5754 -[FBSSerialQueue _performNext] + 192
15 FrontBoardServices 0x00000001061c5ac2 -[FBSSerialQueue _performNextFromRunLoopSource] + 45
16 CoreFoundation 0x0000000102d2ba31 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
17 CoreFoundation 0x0000000102d2195c __CFRunLoopDoSources0 + 556
18 CoreFoundation 0x0000000102d20e13 __CFRunLoopRun + 867
19 CoreFoundation 0x0000000102d20828 CFRunLoopRunSpecific + 488
20 UIKit 0x00000001033cf7cd -[UIApplication _run] + 402
21 UIKit 0x00000001033d4610 UIApplicationMain + 171
22 libert2 0x000000010175849f main + 111
23 libdyld.dylib 0x0000000104a4f92d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
以下是方法：
-(void)salvaridnofirebase {
Firebase *ref = [[Firebase alloc] initWithUrl:@"-myFirebaseURL-"];
Firebase *usersRef = [ref childByAppendingPath:@"users"];
NSDictionary *dict = @{ userid: userid };
[usersRef updateChildValues:dict];
}
答案 0 :(得分：0)
你只需要在编码中更加防守。我希望例外情况如下所示：
free为-(void)salvaridnofirebase {
Firebase *ref = [[Firebase alloc] initWithUrl:@"-myFirebaseURL-"];
Firebase *usersRef = [ref childByAppendingPath:@"users"];
NSDictionary *dict = @{ userid: userid }; // HERE
[usersRef updateChildValues:dict];
}
。因此：
userid == nil最好还是在-(void)salvaridnofirebase {
if (userid == nil) {
NSLog(@"Cannot update userid as it's nil");
return;
}
Firebase *ref = [[Firebase alloc] initWithUrl:@"-myFirebaseURL-"];
Firebase *usersRef = [ref childByAppendingPath:@"users"];
NSDictionary *dict = @{ userid: userid };
[usersRef updateChildValues:dict];
}
时不要调用此方法。你有完全控制权。