Swift控件--UIImageView、UISegmentedControl

UIImageView

 //创建一个图片视图
let imageView = UIImageView(image: UIImage(named: "qiongenxuenuo"))
//设置图片的大小位置
 imageView.frame = CGRect(x: 0, y: 0, width: SCWith, height: (imageView.image?.size.height)!)
//将图片添加到里面控制器视图
view.addSubview(imageView)
 //保持图片比例
imageView.contentMode = .scaleAspectFit

从网络加载图片

let url = URL(string:"http://dl.bizhi.sogou.com/images/2012/01/19/191337.png")!
 //从网络获取数据流
var dataV = Data()
do {
      let data = try Data(contentsOf: url)
      dataV = data
} catch {
       print("出现异常")
}
 //通过数据流初始化图片
let dataImageView = UIImageView(image: newImage)
dataImageView.frame = CGRect(x: 0, y: imageView.frame.size.height, width: 120, height: 80)
view.addSubview(dataImageView)

从网络加载图片时，需要在项目的info.plist文件中添加一个App Transport Security Settings属性，并将该字典下的Allow Arbitrary Loads的值设为设为YES
在使用到Data的方法的时候，编译出现错误“Call can throw, but it is not marked with try; and the error is not handled”，该错误的意思是需要抛出异常，抛出异常主要有三种方法
方式一:try方式,手动捕捉异常

do {
        let data = try Data(contentsOf: url)
        dataV = data
} catch {  
        // error异常的对象
       print(error)
}

方式二:try?方式(常用方式) 系统帮助我们处理异常,如果该方法出现了异常,则该方法返回nil.如果没有异常,则返回对应的对象

guard let dataV = try? Data(contentsOf: url) else {
      return
}

方式三:try!方法(不建议,非常危险) 直接告诉系统,该方法没有异常.注意:如果该方法出现了异常,那么程序会报错(崩溃)
let dataV = try! Data(contentsOf: url)

UISegmentedControl分段选择器

//按钮的选择项
 let items = ["第一" as AnyObject, "第二" as AnyObject, "第三" as AnyObject] as [AnyObject]
let segmentedController = UISegmentedControl(items: items)
segmentedController.frame = CGRect(x: 0, y: SCHight / 2, width: SCWith, height: 44)
//默认选中页
segmentedController.selectedSegmentIndex = 0
//添加只是改变监听
segmentedController.addTarget(self, action: #selector(segmentChange(segmented:)), for: .valueChanged)
view.addSubview(segmentedController)
//添加选项
segmentedController.insertSegment(withTitle: "第四", at: items.count, animated: true)
 //移除选项
//segmentedController.removeSegment(at: items.count, animated: true)
//修改选项的颜色
segmentedController.tintColor = UIColor.orange
//修改选项的文字
segmentedController.setTitle("第五", forSegmentAt: 0)
//修改选项内容便宜位置
//segmentedController.setContentOffset(CGSize(width: 20, height: 10) , forSegmentAt: 1)
//设置背景颜色
segmentedController.backgroundColor = UIColor.black

监听方法

func segmentChange(segmented: UISegmentedControl) {
        //获得选项的索引
        print(segmented.selectedSegmentIndex)
        //获得选项文字如果为图片，则输出为空
        switch segmented.selectedSegmentIndex {
        case 0:
            print(segmented.titleForSegment(at: segmented.selectedSegmentIndex))
        case 1:
            print(segmented.titleForSegment(at: segmented.selectedSegmentIndex))
        case 2:
            print(segmented.titleForSegment(at: segmented.selectedSegmentIndex))
        case 3:
            print(segmented.titleForSegment(at: segmented.selectedSegmentIndex))
        default:
            print(segmented.titleForSegment(at: segmented.selectedSegmentIndex))
        }
}