iOS開発はjsonがNullエラーを返す問題を解決する
3529 ワード
Category--NullSafe.m、運行時に操作して、空の値Nullをnilに置いて、nilは安全で、nilオブジェクトにいかなるmessageを送ることができて、このcategoryを潰さないでとても便利で、工事の中に参加すればGithubアドレスができます;https://github.com/nicklockwood/NullSafe](https://github.com/nicklockwood/NullSafe
ソース:
ソース:
#import
#import
#ifndef NULLSAFE_ENABLED
#define NULLSAFE_ENABLED 1
#endif
#pragma GCC diagnostic ignored "-Wgnu-conditional-omitted-operand"
@implementation NSNull (NullSafe)
#if NULLSAFE_ENABLED
- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector
{
@synchronized([self class])
{
//look up method signature
NSMethodSignature *signature = [super methodSignatureForSelector:selector];
if (!signature)
{
//not supported by NSNull, search other classes
static NSMutableSet *classList = nil;
static NSMutableDictionary *signatureCache = nil;
if (signatureCache == nil)
{
classList = [[NSMutableSet alloc] init];
signatureCache = [[NSMutableDictionary alloc] init];
//get class list
int numClasses = objc_getClassList(NULL, 0);
Class *classes = (Class *)malloc(sizeof(Class) * (unsigned long)numClasses);
numClasses = objc_getClassList(classes, numClasses);
//add to list for checking
NSMutableSet *excluded = [NSMutableSet set];
for (int i = 0; i < numClasses; i++)
{
//determine if class has a superclass
Class someClass = classes[i];
Class superclass = class_getSuperclass(someClass);
while (superclass)
{
if (superclass == [NSObject class])
{
[classList addObject:someClass];
break;
}
[excluded addObject:NSStringFromClass(superclass)];
superclass = class_getSuperclass(superclass);
}
}
//remove all classes that have subclasses
for (Class someClass in excluded)
{
[classList removeObject:someClass];
}
//free class list
free(classes);
}
//check implementation cache first
NSString *selectorString = NSStringFromSelector(selector);
signature = signatureCache[selectorString];
if (!signature)
{
//find implementation
for (Class someClass in classList)
{
if ([someClass instancesRespondToSelector:selector])
{
signature = [someClass instanceMethodSignatureForSelector:selector];
break;
}
}
//cache for next time
signatureCache[selectorString] = signature ?: [NSNull null];
}
else if ([signature isKindOfClass:[NSNull class]])
{
signature = nil;
}
}
return signature;
}
}
- (void)forwardInvocation:(NSInvocation *)invocation
{
invocation.target = nil;
[invocation invoke];
}
#endif
@end