NSObject
- 值类型:
- NSAffineTransform
- NSCalendar
- NSCache
- NSValue
- NSValue
- NSNumber
- NSDecimalNumber
- NSData
- NSMutableData
- NSPurgeableData
- NSDate
- NSDateComponents
- NSDecimalNumberHandler
- NSLocale
- NSNull
- NSTimeZone
- NSValueTransformer
- XML
- NSXMLParser
- Strings
- NSAttributedString
- NSCharacterSet
- NSString
- NSFormatter
- NSDateFormatter
- NSNumberFormatter
- NSScanner
- NSSortDescriptor
- Collections
- NSArray
- NSMutableArray
- NSDictionary
- NSMutableDictionary
- NSNumerator
- NSDirectoryEnumerator
- NSHashTable
- NSIndexPath
- NSIndexSet
- NSMutableIndexSet
- NSMapTable
- NSPointerArray
- NSPointerFunctions
- NSSet
- NSMutableSet
- NSCountedSet
- NSArray
- Predicates
- NSExpression
- NSPredicate
- NSComparisonPredicate
- NSCompoundPredicate
- Operating-System Services
- NSError
- NSHost
- NSNetService
- NSNetServiceBrowser
- NSOrthography
- NSProcessInfo
- NSRunLoop
- NSSpeliServer
- NSTextCheckingResult
- NSTimer
- NSUserDefaults
- File System
- NSBundle
- NSFileHandler
- NSFileManager
- NSMetadataItem
- NSMetadataQuery
- NSMetadataQueryAttributeValueTuple
- NSMetadataQueryResuleGroup
- NSStream
- NSInputStream
- NSOutputStream
- URL
- NSCachedURLResponse
- NSHTTPCookie
- NSHTTPCookieStorage
- NSURL
- NSURLAuthorizationChallenge
- NSURLCache
- NSURLSession
- NSURLCredential
- NSURLCredentialStorage
- NSURLDownload
- NSURLProtectionSpace
- NSURLProtocol
- NSURLRequest
- NSMutableURLRequest
- NSURLResponse
- NSHTTPURLResponse
- Interprocess Communication
- NSPipe
- NSPort
- NSMachPort
- NSMessagePort
- NSSockerPort
- NSPortMessage
- NSPortNameServer
- NSMachBootstrapServer
- NSMessagePortNameServer
- NSSockerPortNameServer
- Locking-Threading
- NSConditionLock
- NSDistributedLock
- NSLock
- NSOperation
- NSBlockOperation
- NSInvocationOperation
- NSOperationQueue
- NSRecursiveLock
- NSTask
- NSThread
- Notifications
- NSNotification
- NSNotificationCenter
- NSNotificationQueue
- Archiving and Serialization
- NSCoder
- NSArchiver
- NSKeyedArchiver
- NSKeyedUnArchiver
- NSPortCoder
- NSUnarchiver
- NSPropertyListSerialization
- NSCoder
- Objective-C Language Service
- NSSeertionHandler
- NSAutoreleasePool
- NSClassDescription
- NSException
- NSInvocation
- NSMethodSignature
- NSUndoManager
NSProxy
- [NSProxy1](https://blog.csdn.net/shubinniu/article/details/80895450)
- [消息转发](https://blog.csdn.net/liyanjun201/article/details/82620485)
- [NSProxy1](https://juejin.im/post/5afbca7bf265da0b8c25251d)
- NSProxy可以帮助Objective-C间接的实现多重继承的功能。
- OC 中一个类只有一个父类, 这就是单一继承, 但是我们可以用协议和 NSProxy 实现多继承