아이폰 앱 개발 팁(11) : Head First iPhone Development #2

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> Head First iPhone Development #2

Chapter 2. iPhone app patterns - Hello @twitter!

App develop process

1. Determine app layout
2. Build the GUI
3. Figure out how to use the controls
4. Handle the data
5. Send output to Twitter

The life of a root view

1. Like in most other languages, main(...) gets called first.
2. Main kicks off a Cocoa Touch Application.
3. MainWindow.xib contains the connections for our application.
4. The Cocoa Touch framework creates our custom view from the InstaTwitViewController.xib.
5. When events occur with components, methods are invoked on our controller instance.

Development process

1. First, declare that the controller conforms to both protocols(UIPickerViewDataSource, UIPickerViewDelegate).
2. Next, add Mike's activities and feelings to the implementation file.
3. The datasource protocol has two required methods(numberOfComponentsInPicerView:pickerView, pickerView:numberOfRowsInComponent).
4. Connect the datasource just like actions and outlets.
5. There's just one method for the delegate protocol(pickerView:titleForRow:forComponent).
6. Add the IBOutlet and property to our view controller.
7. Connect the picker to our outlet.
8. Use our picker reference to pull the selected values(selectedRowInComponent).

@ vs. * : The "@" before those strings tells the compiler to make them NSString instead of char*. NSStrings are real Objective-C classes, as opposed to a simple C-style character pointer.

Added/Modified contents in .h file

@interface InstaTwitViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>
{
    IBOutlet UIPickerView *tweetPicker; 
    NSArray* activities;
    NSArray* feelings;
}

@property (nonatomic, retain) UIPickerView* tweetPicker;
- (IBAction)sendButtonTapped: (id)sender;

Added/Modified contents in .m file

@implementation InstaTwitViewController
@synthesize tweetPicker;

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 2;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    if(component == 0)
    {
        return [activities count];
    }else{
        return [feelings count];
    }
}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger) component
{
    switch (component)
    {
        case 0:
            return [activities objectAtIndex:row];
        case 1:
            return [feelings objectAtIndex:row];
    }
    return nil;
}

- (IBAction)sendButtonTapped: (id)sender
{
    NSString* themessage = [NSString stringWithFormat:@"I'm %@ and feeling %@ about it.", [activities objectAtIndex:[tweetPicker selectedRowInComponent:0]], [feelings objectAtIndex:[tweetPicker selectedRowInComponent:1]]];
    NSLog(themessage);
    //NSLog(@"Tweet button tapped!");

    NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://ID:PW@twitter.com/statuses/update.xml"] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
    [theRequest setHTTPMethod:@"POST"];
    [theRequest setHTTPBody:[[NSString stringWithFormat:@"status=%@", themessage] dataUsingEncoding:NSASCIIStringEncoding]];
    NSURLResponse* response;
    NSError* error;
    NSData* result = [NSURLConnection sendSynchronousRequest:theRequest returningResponse:&response error:&error];
    NSLog(@"%@", [[[NSString alloc] initWithData:result encoding:NSASCIIStringEncoding] autorelease]);
}

- (void)viewDidLoad
{
    activities = [[NSArray alloc] initWithObjects:@"sleeping", @"eating", @"working", @"thinking", @"crying", @"begging", @"leaving", @"shopping", @"hello worlding", nil];
    feelings = [[NSArray alloc] initWithObjects:@"awesome", @"sad", @"happy", @"ambivalent", @"nauseous", @"psyched", @"confused", @"hopeful", @"anxious", nil];
    [super viewDidLoad];
}

- (void)dealloc
{
    [tweetPicker release];
    [activities release];
    [feelings release];
    [super dealloc];
}