PickerView in Objective-C - objective-c

Question

After I enter the following link, the device just display the black screen. Could anyone can please answer what is the problem? Actually, I am wondering the problem is occurring in this part:
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
inComponent:(NSInteger)component{
picCode = [cameraCode objectAtIndex:row];
}
Source Code:
//testingProgram.h
#import <UIKit/UIKit.h>
#interface testingProgramViewController : UIViewController
<UIPickerViewDelegate, UIPickerViewDataSource>
{
NSTimer *aTimer;
NSString *picCode;
UIPickerView *regionPicker;
NSArray *regionNames;
NSArray *cameraCode;
UILabel *testingLabel;
UITextField *regionTextField;
}
#property (nonatomic, retain) IBOutlet UIPickerView *regionPicker;
#property (nonatomic, retain) IBOutlet UILabel *testingLabel;
#property (nonatomic, retain) IBOutlet UITextField *regionTextField;
#property (nonatomic, retain) NSArray *regionNames;
#property (nonatomic, retain) NSArray* cameraCode;
-(IBAction)textFieldReturn:(id)sender;
#end
//testingProgram.m
#import "testingProgramViewController.h"
#interface testingProgramViewController ()
#property (weak, nonatomic) IBOutlet UIImageView *testingPic;
#end
#implementation testingProgramViewController
#synthesize regionPicker, regionNames, cameraCode;
#synthesize testingLabel, regionTextField;
#pragma mark -
#pragma mark PickerView DataSource
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
return [regionNames count];
}
- (NSString *)pickerView:(UIPickerView *)pickerView
titleForRow:(NSInteger)row
forComponent:(NSInteger)component {
return [regionNames objectAtIndex:row];
}
#pragma mark -
#pragma mark PickerView Delegate
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
inComponent:(NSInteger)component{
picCode = [cameraCode objectAtIndex:row];
}
- (void) obtainPic:(NSString *)picName{
NSString *urlLink = [[NSString alloc] initWithFormat:#"http://tdcctv.data.one.gov.hk/%#.JPG", picName];
NSURL *url = [NSURL URLWithString:urlLink];
UIImage *image = [UIImage imageWithData: [NSData dataWithContentsOfURL:url]];
self.testingPic.image = image;
}
-(IBAction)textFieldReturn:(id)sender {
[sender resignFirstResponder];
}
-(void)timerFired:(NSTimer *) theTimer {
[self obtainPic:picCode];
}
- (void)viewDidLoad {
[super viewDidLoad];
self.regionNames = [[NSArray alloc] initWithObjects:
#"Hong Kong Island", #"Kowloon", #"Tsuen Wan",
#"Tuen Mun & Tin Shui Wai", #"Tai Po, North and Yuen Long", #"Shatin & Ma On Shan", #"Lantau", nil];
self.cameraCode = [[NSArray alloc] initWithObjects: #"H429F", #"K202F", #"TW117F", #"TI101F", #"BC702F", #"ST115F", #"TC551F", nil],
picCode = #"H422F2";
[self obtainPic:picCode];
aTimer = [NSTimer scheduledTimerWithTimeInterval:60.0
target:self
selector:#selector(timerFired:)
userInfo:nil
repeats:YES];
}
#end