关于项目中出现 nsnull 的崩溃问题

百度了一下  

写了一个category 方法 来处理这个崩溃的问题

#import "NSNull+OVNatural.h"

@implementation NSNull (OVNatural)

- (void)forwardInvocation:(NSInvocation *)invocation

{

    if ([self respondsToSelector:[invocation selector]]) {

        [invocation invokeWithTarget:self];

    }

}

- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector

{

    NSMethodSignature *sig = [[NSNull class] instanceMethodSignatureForSelector:selector];

    if(sig == nil) {

        sig = [NSMethodSignature signatureWithObjCTypes:"@^v^c"];

    }

    return sig;

}