IOS9 新加关键字 nullable、nonnull、null_unspecified、null_resettable

#import "ViewController.h"

@interface ViewController ()

@property(nonatomic,nullable)NSString*name;//可以为空
@property(nonatomic,nonnull)NSString*password;//不可为空
@property(nonatomic,null_unspecified)NSString*unkonw;//未知类型

@property(nonatomic)NSString* _Nullable name1;//可以为空
@property(nonatomic)NSString* _Nonnull password1;//不可为空
@property(nonatomic)NSString* _Null_unspecified unkonw1;//未知类型

@property(nonatomic)NSString* __nullable name2;//可以为空
@property(nonatomic)NSString* __nonnull password2;//不可为空
@property(nonatomic)NSString* __null_unspecified unkonw2;//未知类型

@property(nonatomic,null_resettable)NSString*setStr;//get方法不能为空，set方法可以为空

-(void)creatDemoWithName:(nullable NSString*)name PSW:( NSString* _Nonnull )psw UnkonwStr:(null_unspecified NSString*)unkownStr;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    [self creatDemoWithName:nil PSW:@"heheheh" UnkonwStr:nil];

}

-(void)setSetStr:(NSString *)setStr{

   self.setStr = @"hehehe";

}

-(void)creatDemoWithName:(nullable NSString*)name PSW:( NSString* _Nonnull )psw UnkonwStr:(null_unspecified NSString*)unkownStr{

    NSLog(@"%@=%@=%@",name,psw,unkownStr);

}