IOS开发，添加控件（xcode9.1 Object-c）

1. 添加文本与编辑框：

UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(20, 20, 200,40)];
    label.backgroundColor = [UIColor blueColor];
    label.textColor = [UIColor blackColor];
    label.text = @"Mylabel";
    [label setFont:[UIFont boldSystemFontOfSize:14]];
    [self.view addSubview:label];
    
    UITextField *textField = [[UITextField alloc]initWithFrame:CGRectMake(20, 70, 260, 30)];
    textField.borderStyle = UITextBorderStyleRoundedRect;
    textField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
    [textField setFont:[UIFont boldSystemFontOfSize:14]];
    textField.placeholder = @"input your text";
    textField.delegate = self;
    [self.view addSubview:textField];

2. 添加ImageView：

-(void) addImageView{
    UIImageView *image = [[UIImageView alloc]initWithFrame:CGRectMake(30, 110, 400,300)];
    [image setImage:[UIImage imageNamed:@"test.jpg"]];
    [image setContentMode:UIViewContentModeScaleAspectFit];
    [self.view addSubview:image];
}

这里要注意的是，只把图片放到相关目录下是不行的，需要打开xcode，把图片资源拖到项目结构中才行。

3. 旧式对话框

-(void) addAlertView{
    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"My Alert" message:@"Are you sure?" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil];
    [alert show];
}

-(void) alertView:(UIAlertView*)alert clickedButtonAtIndex:(NSInteger)buttonIndex{
    switch(buttonIndex){
        case 0:
            NSLog(@"Cancel is clicked.");
            break;
        case 1:
            NSLog(@"Ok is clicked.");
            break;
        default:
            break;
    }
}

在viewDidLoad中调用：[self addAlertView]; 同时在头文件中添加代理：
@interface ViewController : UIViewController<UITextFieldDelegate, UIAlertViewDelegate>
4.新式对话框：

-(void) addAlertControler{
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"New Alert" message:@"Confirm you operations" preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *leftAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        NSLog(@"Cancel is clicked.");
    }];
    UIAlertAction *rightAction = [UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        NSLog(@"Ok is clicked.");
    }];
    [alertController addAction:leftAction];
    [alertController addAction:rightAction];
    [self presentViewController:alertController animated:YES completion:nil];
}

presentViewController必须在视图完全加载后才能调用，所以在viewDidLoad中调用
[self addAlertControler];是无效的，不会显示对话框，log中会提示：
Warning: Attempt to present <UIAlertController: 0x7f901d845a00> on <ViewController: 0x7f901cc0bff0> whose view is not in the window hierarchy!

可以在按钮事件中调用：

- (IBAction)onStartBtnClick:(UIButton *)sender {
    [_mHello setText:@"Start Clicked"];
    [self addAlertControler];
}

结果显示：

来源：CSDN

作者：dingpwen

链接：https://blog.csdn.net/dingpwen/article/details/104374297