Instance variable not retaining value in iOS application
I have declared this ivar in my
ViewController.h
#import <UIKit/UIKit.h>
@interface FirstViewController : UIViewController <UITableViewDelegate, UITableViewDataSource>
{
NSArray *sortedCountries;
}
@property (nonatomic, retain) NSArray *sortedCountries;
@end
In ViewController.m, sortedCountries does it's job in -(void)ViewDidLoad{}
by storing the result of a sorted .plist.
When
-(UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {}
is called below, sortedCountries returns (null)
Why doesn't the value of sortedCountries remain? I added a retain
in the first function... I think I am missing a fundamental Objective-C tenant here.
ViewController.m
#import "FirstViewController.h"
@implementation FirstViewController
@synthesize sortedCountries;
-(void)viewDidLoad {
NSString *path = [[NSBundle mainBundle] pathForResource:@"countries" ofT开发者_JAVA百科ype:@"plist"];
NSArray *countries = [NSArray arrayWithContentsOfFile:path];
NSSortDescriptor *descriptor = [[[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES] autorelease];
NSArray *sortedCountries = [[countries sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]]retain];
}
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
-(NSInteger)tableView:(UITableView *)tableView
numberOfRowsInSection:(NSInteger)section {
return 236;
}
-(UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {
NSDictionary *country = [sortedCountries objectAtIndex:indexPath.row];
NSLog(@"countryDictionary is: %@",country);
NSString *countryName = [country objectForKey:@"name"];
NSLog(@"countryName is : %@", countryName);
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell =
[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier] autorelease];
}
cell.textLabel.text = countryName;
return cell;
}
NSArray *sortedCountries = [[countries sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]]retain];
to
self.sortedCountries = [countries sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]];
You are re-declaring sortedCountries
as a local variable in viewDidLoad
. Use:
sortedCountries = ...
instead (notice no NSArray *
). In the code you are using now, sortedCountries
would be populated in viewDidLoad
, but accessible only in viewDidLoad
. You were creating a new variable with the same name instead of setting the class property.
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