Common UI Controls and Events

UI Controls: Your App's Face

Displaying Text with UILabel

UILabel in Action

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // Create a label with a frame (position and size)
        UILabel *myLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 50, 280, 40)];
        myLabel.text = @"Hello CoddyKit!";
        myLabel.textColor = [UIColor darkTextColor];
        myLabel.font = [UIFont boldSystemFontOfSize:20.0];
        myLabel.textAlignment = NSTextAlignmentCenter;

        NSLog(@"Created UILabel:");
        NSLog(@"  Text: %@", myLabel.text);
        NSLog(@"  Font Size: %.1f", myLabel.font.pointSize);
        NSLog(@"  Alignment: %ld", (long)myLabel.textAlignment);
    }
    return 0;
}

Making Apps Interactive with UIButton

Responding to Button Presses

Implementing a Tap Action

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface ButtonHandler : NSObject
- (void)buttonTapped:(UIButton *)sender;
@end

@implementation ButtonHandler
- (void)buttonTapped:(UIButton *)sender {
    NSLog(@"Button '%@' was tapped!", [sender titleForState:UIControlStateNormal]);
}
@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        ButtonHandler *handler = [[ButtonHandler alloc] init];

        UIButton *myButton = [UIButton buttonWithType:UIButtonTypeSystem];
        myButton.frame = CGRectMake(10, 100, 200, 50);
        [myButton setTitle:@"Press Me!" forState:UIControlStateNormal];
        
        // Set up the target-action. The handler object will receive the message.
        [myButton addTarget:handler 
                     action:@selector(buttonTapped:)
           forControlEvents:UIControlEventTouchUpInside];

        NSLog(@"Button created. If tapped, console would show action.");
        // In a real app, you'd add myButton to a view hierarchy.
        // For this console example, we simulate the action call.
        // [handler buttonTapped:myButton]; // Uncomment to simulate a tap immediately
    }
    return 0;
}

Accepting Text with UITextField

Handling UITextField Events

Observing Text Input

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface TextFieldHandler : NSObject
- (void)textFieldDidChange:(UITextField *)sender;
@end

@implementation TextFieldHandler
- (void)textFieldDidChange:(UITextField *)sender {
    NSLog(@"Text field content changed: %@", sender.text);
}
@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        TextFieldHandler *handler = [[TextFieldHandler alloc] init];

        UITextField *myTextField = [[UITextField alloc] initWithFrame:CGRectMake(10, 160, 280, 40)];
        myTextField.placeholder = @"Type here...";
        myTextField.borderStyle = UITextBorderStyleRoundedRect;
        
        // Attach an action for when the text changes
        [myTextField addTarget:handler
                        action:@selector(textFieldDidChange:)
              forControlEvents:UIControlEventEditingChanged];

        NSLog(@"Text field created. Simulating input...");
        // Simulate some input changes
        myTextField.text = @"H";
        [handler textFieldDidChange:myTextField];
        myTextField.text = @"He";
        [handler textFieldDidChange:myTextField];
        myTextField.text = @"Hello";
        [handler textFieldDidChange:myTextField];
    }
    return 0;
}

Identify the UI Control

Recap: Common Controls & Events