objective c - Is a CGContext an object? -


I've been programming for 2 months (so I am quite new) and I am currently learning how to attract Graphics for an iPhone app but I need clarification on CGContext . To create the current reference we use CGContextRef currentContext = UIGraphicsGetCurrentContext () , if here I understand well (and please correct me if I am wrong), UIGraphicsGetCurrentContext () On the current context, we provide it on an indicator type CGContexRef . Is there an object allocated to memory on the heap in the current context, or is it only a type of variable on the stack? I know that we use the pointer to work with the same data and avoid copying the big memory block (right?), But actually a CGContext , an object, a Straight or whatever?

These opaque types mean that you do not have to know and there is no need to take care . Apple can change its interior with every release and we do not know (and it is not needed). Typically, the FooRef type is the indication of something, now it has been defined: 

  typedef struct CGContext * CGContextRef;   
 But what if  struct CGContext  looks like this, we do not know. Generally maintain / release functions are:  
  CGContextRef CGContextRetain (CGContextRef c); It  looks  as if it is actually the core forwardness (and perhaps Objective-C) object; Zero CGContextRelease (CGContextRef C);   
 Common Core Foundation memory naming patterns apply: You do not need to issue  CGContextRef   or  copy .

Comments

Post a Comment

Popular posts from this blog

Java - Error: no suitable method found for add(int, java.lang.String) -

I'm in the middle of homework work and I'm stuck. At this point in my code, I think that I should have a GUI window that opens and allows me to type "inserted text number". Notice is not going anywhere but at this point, If I pass through the problem then it will be in a linked list. I am getting two of the same error for the lines. Add (index, element); And I can not seem to get past it, there is no suitable method for the error "add (int, java. string string)". Code is below, please advise. To clarify - this will not be a method error because it is a linked list. There should not be any way involved. import java.awt. *; Import java.awt.event. *; Import javax.swing. *; Import java.util. *; Import java.util.Scanner; Import java.util.LinkedList; Public class TopTenList JFrame {Private TopTenList tt; See the Private JTextArea list; Private JTextField cmdTextField; Private JTextField resultsTestfield; // This GUI window is the code for the public toptist...
Read more

java - JPA TypedQuery: Parameter value element did not match expected type -

I am using JPA 2.0 and getting the following code in the DAO layer: Public Zero Test () {string key = "status"; String [] Conditions = {"A", "B"}; & Lt; TestTable & gt; Results = Search (Keys, Conditions); } Public listing & lt; TestTable & gt; Search (string key, object value error) {string sql = "test ndf to testlet and jade nand." + Key + "in:" + key; TypedQuery & LT; TestTable & gt; Query = entityManager.createQuery (SQL, TestTable.class); Query.setParameter (key, Arrays.asList (valueArr)) / *** Error Line *** Return query.getResultList (); } In the above error line, it throws the following exception: java.lang.IllegalArgumentException: parameter value element [[Ljava.lang.String; @ cbe5bc] did not match the expected type [java.lang.String] Why is this expected type string while actually this string []? Please help! Note: This is derived from the normal routine and is a simplified code. I can no...
Read more

c++ - static template member variable has internal linkage but is not defined -

Yes, I know, there is a question with almost the same title, but it refers to a different situation. Error message) In my case, I have a .cpp file with a big named designation name (implementation details). There is a property class template with a static data member in that name space, which I need to access from outside the unknown namespace. I give it a little bit of meat: file.hpp namespace Bar {template & lt; Typename A & gt; Struct foo {static_assert (is_same & lt; a, float & gt; :: value} is_same & lt; a, double>: value, ""); Fixed zero set_static_var (a const & x); // ...}; } and file.cpp namespace {template & lt; Typename A & gt; Struct foo_traits {// supports the implementation of several static code bars: foo & lt; & Gt; Fixed A data; }; The template's & lt; & Gt; Float foo_traits & lt; Float & gt; :: datum; // No change if this is in the global namespace template & lt; & Gt; Doub...
Read more