swift 基础小结01 --delegate、Optional、GCD的使用、request请求、网络加载图片并保存到沙箱、闭包以及桥接

  本文主要记录swift中delegate的使用、“?!”Optional的概念、GCD的使用、request请求、网络加载图片并保存到沙箱、闭包以及桥接。


一、delegate的使用

swift中delegate的使用和objective-c大同小异,简单记录一下:

  step1:声明

@objc protocol testProtocol:NSObjectProtocol{
@objc optional func testAdd( a:Int, b:Int) -> Int; }

  step2:实例化

class TextFieldViewController: UIViewController ,UITextFieldDelegate{
var delegate:testProtocol!
}

  step3:调用delegate响应(此处没有处理delegate为空的情况,因为使用了“?”,当delegate为nil的时候,后面的testAdd不会被执行)

//        if (self.delegate != nil)&&(self.delegate?.responds(to:#selector(testProtocol.testAdd(a:b:))))!{
//            let result = self.delegate!.testAdd!(a: 2, b: 5)
//            print(result)
//        }
        let result = self.delegate?.testAdd!(a: 3, b: 1)
        print(result ?? "delegate没有响应")

  step4:其他类遵循并实现协议

class UIBaseViewController: UIViewController,UITableViewDataSource,UITableViewDelegate,testProtocol{
func testAdd( a:Int, b:Int) -> Int{
print(a+b)
return a+b
}
func jump{
let txtVC = TextFieldViewController()
txtVC.delegate = self
self.navigationController?.pushViewController(txtVC, animated: true)
}
}

二、“? !”的使用和含义

详细深层的理解,请Google,百度,下面简单记录使用时的区别

            self.navigationController?.pushViewController(txtVC, animated: true)

上面的“?”处理逻辑是,当navigationController为nil时直接不执行后面的push操作,当navigationController存在时执行后面的push操作。

self.navigationController!.pushViewController(txtVC, animated: true)

上面的“!”对UINavigationController?进行了手动解包,也就是说navigationController绝对存在,否则(navigationController为nil)程序就会直接崩溃。

三、GCD使用

  

  1、同步

    func dispatch_sync(){
let queue = DispatchQueue(label: "com.test.queuesync")
queue.sync {
for i in ...{
print("sync test --- ",i)
}
print(" ---同步执行结束 子线程---")
}
}

  

  2、异步

    func dispatch_async(){
let queue = DispatchQueue(label: "com.test.queueasync")
queue.async {
for i in ...{
print("async test --- ",i)
}
print(" ---异步执行结束 子线程---")
}
}

  

  3、延时

    func dispatch_delay(){
let queue = DispatchQueue(label: "com.test.queuedelay")
queue.asyncAfter(deadline: DispatchTime.now()+DispatchTimeInterval.seconds(), execute: { print(" ---延迟执行执行结束 子线程---")
})
}

  

  4、回到主线程

    func dispatch_main(){

        let queue = DispatchQueue(label: "com.test.backtomain")
queue.async{
DispatchQueue.main.sync {
print(" ---回到主线程---")
}
}
}

  5、全局并发队列

        func dispatch_global(){
let queue = DispatchQueue.global()
let workItem = DispatchWorkItem{
print("调用了workitem")
}
queue.async {
for i in ...{
print("async test --- ",i)
}
workItem.perform();
print(" ---global异步执行结束 子线程---")
}
}

四、request

  

  1、GET请求

    func getRequest(){
let url = URL.init(string: "https://api.github.com/repos/alibaba/weex")
let request = NSMutableURLRequest.init(url:url!) request.httpMethod = "GET" request.timeoutInterval =
// let params = "type=shentong&postid=3333557693903" as NSString
// request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
// request.httpBody = params.data(using: String.Encoding.utf8.rawValue) let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest) { (data, response, error) -> Void in
if (error != nil) {
print(error ?? "")
return
}else {
//此处是具体的解析,具体请移步下面
do{
let json = try JSONSerialization.jsonObject(with: data!, options: [])
print(json)
// let json: Any = try! JSONSerialization.jsonObject(with: data!, options: [])
// print(json)
JYToast.showInMidWindow(title: NSString.init(format: "data is -- \n %@", json as! CVarArg) as String)
}catch{
print(error.localizedDescription)
} }
}
dataTask.resume() }

  

  2、POST请求

func postRequest(){
let url = URL.init(string: "http://www.kuaidi100.com/query")
let request = NSMutableURLRequest.init(url:url!) request.httpMethod = "POST"
request.timeoutInterval =
let params = "type=shentong&postid=3333557693903" as NSString
request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.httpBody = params.data(using: String.Encoding.utf8.rawValue) let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest) { (data, response, error) -> Void in
if (error != nil) {
print(error ?? "")
JYToast.showInMidWindow(title: NSString.init(format: "error is -- \n %@", error! as CVarArg) as String)
return
}else {
do{
let json = try JSONSerialization.jsonObject(with: data!, options: [])
print(json)
JYToast.showInMidWindow(title: NSString.init(format: "data is -- \n %@", json as! CVarArg) as String)
}catch{
print(error.localizedDescription) }
}
}
dataTask.resume()
}

五、加载网络图片并保存到沙箱

let queue = DispatchQueue.global();

queue.async {

let data = NSData.init(contentsOf: NSURL.init(string: "http://c.hiphotos.baidu.com/image/h%3D300/sign=58adc7aa3c2ac65c78056073cbf3b21d/3b292df5e0fe9925de1b729a3da85edf8cb171e0.jpg")! as URL)
let image = UIImage.init(data: data! as Data)
let doc = NSHomeDirectory() as NSString
doc.appendingPathComponent("Documents/1.jpg")

do{
try data?.write(toFile: doc.appendingPathComponent("Documents/1.jpg"), options: NSData.WritingOptions.atomic)
}catch{
print(error.localizedDescription)
}

let main = DispatchQueue.main
main.async {
let imageView = UIImageView.init(frame: CGRect.init(x: , y: , width: , height: ))
imageView.image = image
self.view.addSubview(imageView)
}
}

六、闭包

  闭包和block类似,有逃逸闭包和非逃逸闭包之分

//起别名
typealias AlertHandler = (_ action:UIAlertAction) -> () class JYShowAlert: NSObject {
// 作为参数
class func showAlert(alertTitle:String,message:String,actionTitle:String,handler:@escaping AlertHandler){
let alertVC = UIAlertController.init(title:alertTitle, message: message, preferredStyle: UIAlertControllerStyle.alert)
let confirm = UIAlertAction.init(title: actionTitle, style: UIAlertActionStyle.cancel, handler: handler)
alertVC.addAction(confirm)
let rootVC = UIApplication.shared.keyWindow?.rootViewController
if ((rootVC?.presentedViewController) != nil){
rootVC?.presentedViewController?.present(alertVC, animated: true, completion: nil)
}else{
rootVC?.present(alertVC, animated: true, completion: nil)
} } }

七、桥接文件

  1、新建header-file

  2、如下图导入

swift 基础小结01 --delegate、Optional、GCD的使用、request请求、网络加载图片并保存到沙箱、闭包以及桥接

  3、在文件中加入需要桥接的objective-c的头文件即可

上一篇:HTML5做手机站页面字体显示很小的解决方法


下一篇:Instructions函数对照表:02 xmmintrin.h与SSE指令集[转]