UISwitch用法:

#import "ViewController.h"
@interface ViewController ()
@end

@implementation ViewController{
    UISwitch *_switch;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //创建开关(默认关状态)
    _switch = [[UISwitch alloc]initWithFrame:CGRectMake(0, 200, 100, 40)];
    [self.view addSubview:_switch];
    
    //添加事件switchChange
    [_switch addTarget:self action:@selector(switchChange) forControlEvents:UIControlEventValueChanged];

}

- (void)switchChange{
    if (_switch.isOn) {
        NSLog(@"开");
    }else{
        NSLog(@"关");
    }
}

// 控件大小，不能设置frame，只能用缩放比例

 _switch.transform = CGAffineTransformMakeScale(0.8, 0.8);