Objective C why are the objects from my NSMutableArray disappearing? - ios

Question

I'm new to Objective-C and iOS. I'm having trouble with something that is probably easily corrected, but I have no idea why it's happening.
I'll try to give a brief description of what I'm doing and hopefully it'll have enough info to spot the error.
PolygonView.h is a UIView type class, and it declares the NSmutablearray like this:
#property(nonatomic, retain) NSMutableArray *polys;
I init it in PolygonView.m's initWithFrame:(CGRect)Frame method like this:
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
polys = [[NSMutableArray alloc]init];
[self loadCsv];
return self;
}
inside loadCSV I load a csv use it to create a few poly objects and do some other stuff, but here's the gist of it:
poly* p;
p = [[poly alloc] init];
// here I set a few properties on p from the csv file and then add p to polys like this:
[polys addObject:p];
At the end of the method I use nslog to print the count like this:
NSLog(#"polys size = %i", [polys count]);
This prints "polys size = 100" on the console.
And then I decided to do my own drawRect. and the beginning of it use the same nslog to print the size/count, but "polys size = 0" is printed on the console.
What am I doing wrong? how can I access the objects I added to this array from the drawRect method?
edit:
here's the full polygonView.h file:
#import <UIKit/UIKit.h>
#interface PolygonView : UIView{
NSMutableArray *polys;
}
#property(nonatomic, retain) NSMutableArray *polys;
-(void)loadCSV;
#end
edit 2: the full polygon
//
// PolygonView.m
// Polygon2
//
#import "PolygonView.h"
#import "poly.h"
#implementation PolygonView
#synthesize polys;
-(id)init
{
NSLog(#"regular init");
self = [super init];
if (self) {
self.polys = [[NSMutableArray alloc]init];
[self loadCsv];
}
return self;
}
- (id)initWithFrame:(CGRect)frame
{
NSLog(#"init with frame");
self = [super initWithFrame:frame];
if (self) {
self.polys = [[NSMutableArray alloc]init];
[self loadCsv];
}
return self;
}
-(void)loadCsv
{
poly* p;
NSString *filePath = [[NSBundle mainBundle] pathForResource:#"DivisoesEstaduais" ofType:#"csv"];
NSString *testString = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
NSString *newString = [testString stringByReplacingOccurrencesOfString:#"," withString:#"."];
if (newString) {
NSMutableArray *arrr = [newString componentsSeparatedByString:#"\n"];
for (int i = 0; i < [arrr count]; i++){
if ([[arrr objectAtIndex:i] length] > 0){
p = [[poly alloc] init];
NSMutableArray *arrayatual = [[arrr objectAtIndex:i] componentsSeparatedByString:#";"];
[p setPolyid:[arrayatual objectAtIndex:0]];
[p setPartid:[arrayatual objectAtIndex:1]];
[p setPointid:[arrayatual objectAtIndex:2]];
[p setx:[arrayatual objectAtIndex:3]];
[p sety:[arrayatual objectAtIndex:4]];
[self.polys addObject:p];
NSLog(#"polys size = %i", [self.polys count]); // this increases from 1 to 100
}
}
NSLog(#"polys size = %i", [self.polys count]); // this prints 100
}else{
NSLog(#"not");
}
}
- (void)drawRect:(CGRect)rect{
srandom( time( NULL ) );
CGContextRef context= UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, random() % 250, random() % 250, random() % 250, 1.0);
CGContextSetFillColorWithColor(context, [UIColor redColor].CGColor);
CGContextFillPath(context);
int oldtemp = 0;
NSLog(#"drawRect polys pointer = %#", self.polys); // this is null
NSLog(#"polys size = %i", [self.polys count]); // this is zero
for (int i = 0; i < [polys count]; i++){
poly *p = [polys objectAtIndex:i];
int temp = p.getPolyid.intValue;
if (temp == oldtemp){
CGFloat hue = ( arc4random() % 256 / 256.0 ); // 0.0 to 1.0
CGFloat saturation = ( arc4random() % 128 / 256.0 ) + 0.5; // 0.5 to 1.0, away from white
CGFloat brightness = ( arc4random() % 128 / 256.0 ) + 0.5; // 0.5 to 1.0, away from black
UIColor *color = [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillPath(context);
NSLog(#"movetopoint");
CGContextMoveToPoint(context, [p.getx floatValue]+160, [p.gety floatValue]+160);
oldtemp++;
}else{
CGContextAddLineToPoint(context, [p.getx floatValue]+160, [p.gety floatValue]+160);
NSLog(#"addlinetopoint");
}
}
CGFloat hue = ( arc4random() % 256 / 256.0 ); // 0.0 to 1.0
CGFloat saturation = ( arc4random() % 128 / 256.0 ) + 0.5; // 0.5 to 1.0, away from white
CGFloat brightness = ( arc4random() % 128 / 256.0 ) + 0.5; // 0.5 to 1.0, away from black
UIColor *color = [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillPath(context);
}
#end
and here's viewController.m:
//
// ViewController.m
// Polygon2
//
//
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.multipleTouchEnabled = YES;
PolygonView * pv = [[PolygonView alloc] init];
[self.view addSubview:pv];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
Edit3:
George Sachin's solution worked: use viewDidAppear instead of viewDidLoad. But why was viewDidLoad causing me trouble? Here's the zipped project in case anyone wants to take a look and try to figure out.
http://www.mediafire.com/download/b9ueqkqbmxswd7a/Polygon2_3.zip
Seems to me ViewDidload is the one I should be using. Should I never use it?

Answer 1

Final Edit:
When you create an initializer for a UIView you should always call super's initWithFrame: or initWithCoder: when you use a .xib
Change your code to this:
-(id)init
{
NSLog(#"regular init");
self = [super initWithFrame:CGRectMake(0, 0, 20, 20)]; // Replace with the dimensions you want
if (self) {
self.polys = [[NSMutableArray alloc]init];
[self loadCsv];
}
NSLog(#"(init)polys size = %i", [self.polys count]);
return self;
}

Answer 2

Try to do this:
1) When you're setting #property(nonatomic, retain) myObj to the object you should do in the .m file #synthesize myObj
2) as HSNN says you should access it via self.myObj
3)It's better to do init part in between this part
if (self) {
// Initialization code
}
phrase "initialization code" was put there not accidentally))
Most likely that root of the problem is forgotten #synthesize but it's better to cover all 3 steps.
good luck. feel free to ask if this won't help)