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POHow to store a value of NSString as char array within a structure in Objective-C?
 

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  1. POHow to store a value of NSString as char array within a structure in Objective-C?
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    <p>I am having trouble assigning the value of an <code>NSString</code> to a <code>char *</code> within a structure of a singleton class. The following is a simplification of my problem. My code utilizes more fields in the structure and passes more <code>NSString</code>s.</p> <p>Say I have a singleton class "SingletonClass" with a structure (I've done my homework with the Apple Documentation and implemented it correctly):</p> <pre><code>struct sampleStruct { char *string1; //other fields } struct1; </code></pre> <p>with this method that sets the value of <code>struct1.string1</code> to the NSString that was passed:</p> <pre><code>- (void)initStructWithString:(NSString *)inputString { //warning: assignment discards qualifiers from pointer target type struct1.string1 = [inputString cStringUsingEncoding:NSUTF8StringEncoding]; } </code></pre> <p>and this method that uses <code>struct1.string1</code>:</p> <pre><code>- (void)useCharArray { //I would obviously be doing something more complex in reality printf("This is the char array: %s", struct1.string1); //doesn't print the value I assigned to it, but garbage } </code></pre> <p>When I call <code>initStructWithString:(NSString *)inputString</code> from one class and try to call <code>useCharArray</code> from another class <code>struct1.string1</code> is a bunch of garbage. During debugging I've confirmed that each class is getting the same instance of this <code>SingletonClass</code>.</p> <p>I'm still learning Objective-C as well as C along the way, so I'm aware it could be a problem with my memory management. I know I <code>[NSString cStringUsingEncoding]</code> should be assigned to a <code>const char *</code> and not a <code>char *</code>, but I don't know how else to go about it since the field in the structure is a <code>char *</code>. I've tried other approaches within <code>initSructWithString</code> such as assigning a new <code>const char *</code> the result of <code>[NSString cStringUsingEncoding]</code> and then copying that with <code>strlcpy</code> to <code>struct1.string1</code>. That approach had the same result.</p> <p>What is the correct technique for storing the value of an <code>NSString</code> in a <code>char *</code> within a struct and how can I ensure that the fields within this struct retain their value as the <code>SingletonClass</code> is used by different classes?</p>
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