convert struct to objective c array or class - ios

Question

I m new for IOS. I have some source code for OS X and java. I was trying to convert to IOS.
In OS X, I have the following.
struct _NoteData {
int number; /** The Midi note number, used to determine the color */
WhiteNote *whitenote; /** The white note location to draw */
NoteDuration duration; /** The duration of the note */
BOOL leftside; /** Whether to draw note to the left or right of the stem */
int accid; /** Used to create the AccidSymbols for the chord */
};
typedef struct _NoteData NoteData;
#interface ChordSymbol : NSObject <MusicSymbol> {
_NoteData notedata[20];/** The notes to draw */
}
_NoteData is like an array and class here. number, whitenote,duration..are instance variable for _noteData.
I was trying to change struct to objective c class:
#interface _NoteData:NSObject{
#property NSInteger number_color;
#property WhiteNote *whitenote;
#property NoteDuration duration;
#property BOOL leftside;
#property NSInteger accid;
};
#interface ChordSymbol : NSObject <MusicSymbol> {
_NoteData notedata[20];/** The notes to draw */
}
In my .m file, it has
+(BOOL)notesOverlap:(_NoteData*)notedata withStart:(int)start andEnd:(int)end {
for (int i = start; i < end; i++) {
if (!notedata[i].leftside) {
return YES;
}
}
return NO;
}
!notedata[i] throw error expected method to read array element. I understand _NoteData is a class, not an array. What should I change?
In java:
private NoteData[] notedata;
NoteData is a class, and notedata is an array which store NoteData.
Same method in java
private static boolean NotesOverlap(NoteData[] notedata, int start, int end) {
for (int i = start; i < end; i++) {
if (!notedata[i].leftside) {
return true;
}
}
return false;
}
I feel all I need is to declare an array with _NoteData object. How can I do that?

Answer 1

Objective-C is a superset of C, so you can use C struct in Objective-C code. You can keep your code in the first paragraph. You need to move the function declaration in ChordSymbol class's header file.
+(BOOL)notesOverlap:(NoteData*)notedata withStart:(int)start andEnd:(int)end;
In another Objective-C class's implementation file, call the Class function like this.
NoteData y[] = {
{ .leftside = YES },
{ .leftside = YES },
{ .leftside = YES },
{ .leftside = YES }
};
BOOL result = [ChordSymbol notesOverlap:y withStart:0 andEnd:3];
NSLog(#"%d",result);
Edit
You can use NSArray for this purpose. You create an array and populate its data with NoteData objects.
NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity:20];
NoteData *data1 = [[NoteData alloc] init];
data1.number_color = 1;
[array addObject:data1];
Then you should change (_NoteData*)notedata to (NSArray*)array, and it should work.