iPhone 开发人员需要学习哪些关键概念 [关闭]

objective-c
#import 
@interface ViewController : UIViewController
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}
@end
int main(int argc, char * argv[]) {
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

swift
import UIKit
class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let button = UIButton(type: .system)
        button.frame = CGRect(x: 100, y: 100, width: 200, height: 50)
        button.setTitle("Click me", for: .normal)
        button.addTarget(self, action: #selector(buttonClicked), for: .touchUpInside)
        
        self.view.addSubview(button)
    }
    
    @objc func buttonClicked() {
        print("Button clicked!")
    }
}

swift
import UIKit
struct Person {
    var name: String
    var age: Int
}
class ViewController: UIViewController {
    
    @IBOutlet weak var nameLabel: UILabel!
    @IBOutlet weak var ageLabel: UILabel!
    
    var person: Person?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        person = Person(name: "John Doe", age: 30)
        
        nameLabel.text = person?.name
        ageLabel.text = "\(person?.age ?? 0)"
    }
}

swift
import Foundation
func divide(_ a: Int, _ b: Int) -> Int {
    assert(b != 0, "The divisor cannot be zero!")
    return a / b
}
let result = divide(10, 5)
print("Result: \(result)")