retain

问题 I'm making a skin previewer for my site; I need to rotate parts of an image to create a representation of this for my users to see. The skin is a PNG file, and all parts of it may have transparency or even none at all. I need to be able to rotate this image while keeping any transparency inside the image transparent, while also having the extended borders (You know, the area that wasn't part of the image before it was rotated) transparent. All of my attempts have left a black border around

问题 Just curious if there is anyway to display an objects retain count using NSLog. I just want to print them out to console to help learn how retain/release is working in some simple code? cheers -gary- 回答1: Not only is it possible, it's very easy too: NSLog(@"retain count=%d",[obj retainCount]); 回答2: I think you might be hitting an issue with NSString where retain and release messages can be sent to a string constant, but they actually have no effect nor alter the objects retainCount. The code

问题 What is the difference between copy and retain for NSString ? - (void)setString:(NSString*)newString { string = [newString copy]; } 回答1: In a general setting, retaining an object will increase its retain count by one. This will help keep the object in memory and prevent it from being blown away. What this means is that if you only hold a retained version of it, you share that copy with whomever passed it to you. Copying an object, however you do it, should create another object with duplicate

问题 Here is code I am referring to. // Person.h @interface Person : NSObject { NSString *firstName; NSString *lastName; } @end // Person.m @implementation Person - (id)init { if (![super init]) return nil; firstName = @"John"; lastName = @"Doe"; } @end // MyClass.m @implementation MyClass ..... - (NSArray *)getPeople { NSMutableArray *array = [[NSMutableArray alloc] init]; int i; for (i = 0; i < 10; i++) { Person *p = [[Person alloc] init]; [array addObject:p]; } return array; } ..... @end Now, I

问题 Here is code I am referring to. // Person.h @interface Person : NSObject { NSString *firstName; NSString *lastName; } @end // Person.m @implementation Person - (id)init { if (![super init]) return nil; firstName = @"John"; lastName = @"Doe"; } @end // MyClass.m @implementation MyClass ..... - (NSArray *)getPeople { NSMutableArray *array = [[NSMutableArray alloc] init]; int i; for (i = 0; i < 10; i++) { Person *p = [[Person alloc] init]; [array addObject:p]; } return array; } ..... @end Now, I

问题 I have read a number of questions on this site about this issue, I understand the following: self.property accesses the getter/setter method created manually or by @synthesize. Depending upon whether the property is declared as retain, copy etc. the retain count is modified correctly, for example a retained property, releases the previous value assigned the new value with 'retain' and increments the retain count by 1. Properties are usually declared with instance variables of the same name

问题 I suspect that the following function, which I use in my GameScene class in order to manage the accelerometer's input, is keeping my scene from deinitializing when I transition to another scene: class GameScene: SKScene { let motionManager = CMMotionManager() var xAcceleration = CGFloat(0) // Some stuff // override func didMove(to: .... func setupCoreMotion() { motionManager.accelerometerUpdateInterval = 0.2 let queue = OperationQueue() motionManager.startAccelerometerUpdates(to: queue,

问题 In my last question (here), I had an issue where I was getting an EXC_BAD_ACCESS because I was releasing the variable I had just allocated: NSMutableArray* s = [[NSMutableArray alloc] init]; stack = s; [s release]; should have been NSMutableArray* s = [[NSMutableArray alloc] init]; stack = s; However, stack is a retained property of my class. It's declared like so: @interface StateStack () @property (nonatomic, retain) NSMutableArray* stack; @end I was under the impression that when you

问题 Let's assume I have the following typedef: typedef void (^myBlock)(id); And I have some method myMethod accepting myBlock as an argument and yielding some id variable to it: void myMethod(id myObj, myBlock block) { // ... block(myObj); // ... } So if I have the following: - (void) someMethod { __block id myObj; // Some initialization local to the scope of someMethod; // myObj = ... some assignment to myObj so it is not nil... dispatch_async(someQueue(), ^{ // (*) Some long, possibly multi

问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . Consider I am allocating an object. Please see the below image In the above image *myObject is a pointer. It is referring to an space allocated to that object. When we retain the object, I like to know what it