rong3git

gist 2

rong3git

$ defaults write com.apple.finder AppleShowAllFiles -bool true  

rong3git

NSURL *documentsDirectoryURL = [NSURL fileURLWithPath:
[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]];
NSLog(@"%@",documentsDirectoryURL);

rong3git

@interface ViewController: UIViewController {
    UIView *_demoView;
    BOOL _gameCenterAvailable;
}

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dispatch_group_t groupName = dispatch_group_create(); 

dispatch_group_enter(groupName);

dispatch_group_leave(groupName);

dispatch_group_notify(groupName, dispatch_get_main_queue(), ^(void){})

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var dates: [NSDate]
var words: Set<String>
var cachedData: [NSURL: NSData]

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@property (nonatomic, readonly, copy) NSArray<__kindof NSURL* > *urlArray;
NSURL *getOneURL = self.urlArray.lastObject;

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@property (copy, readonly) NSArray * _Nonnull allItems;
@property (nonatomic, strong, nonnull) Person *personNameA; 
@property (nonatomic, copy, readonly, nullable) NSString *personName; 

+ (nullable NSString *)sayHello:(nonnull NSString *)message;
- (AAPLListItem * _Nullable)itemWithName:(NSString * _Nonnull)name;
- (void)takesNullableParameter:(nullable id)value;

rong3git

class Person {
  var residence: Residence? //Optional default nil value
}
class Residence {
  var numberOfRooms = 1
}

let jay = Person() //jay has a residence property value nil
//runtime error, can't send message to nil 
let roomCount = john.residence!.numberOfRooms //unwrap optional

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@property (nonatomic, strong) NSArray <NSURL *> *demoArray;

- (void)demoMethod {
    NSURL *url1 = [NSURL URLWithString:@"http:www.urldemo1.com"];
    NSURL *url2 = [NSURL URLWithString:@"http:www.urldemo2.com"];
    self.demoArray = @[url1, url2];
}