ios swift 知识点记录

1. 定义变量 var name = "***"

定义常量 let name ="*****"

2. swift 变量类型  String, Int, Float, Double

3. swift 逻辑操作符   &&  ， ||， ！

4. swift 关系运算符 ==, !=, >=, <=

5. swift storyboard界面元素跟code绑定，右键（button , label什么的），左键按住划线到view, 选择对应的code 里的variable or 方法

6. swift 定义类似静态函数： class func methodName() -> type {}

静态变量： static var  name：type =  **** 调用的时候，是className.name() 这样的方式

7. var xxx = Object!  意思是显示转换， “！”代表这个有可能没有值

8. 实例化： myStation = RadioStation.init(name: "KZZP", frequency: 104.7) 或   myStation = RadioStation()

9. 创建新Class， 需要在IDE选Cocoa Touch Class

10.Stretching label， 是自动拉伸，否则，会截断text内容

11.给storyboard 上的button添加方法的另一种操作

12. 数组定义 var myArray: [string] = ["One", "Two"] print(myArray[0])  数组长度：myArray.count  数组扩展：myArray.append("Three"), myArray += ["Four","Five"], myArray.insert("Zero", at: 0) 删除： myArray.remove(at: **)

13. for 循环

for  y in 0 .. <numbers{

}

14. 日期比较  today.compare(date)

15. ios preference 存储

let prefs: UserDefaults = UserDefaults.standard
prefs.set("sherlock.holmes", forKey: "username")
prefs.set(10, forKey: "booksInList")
prefs.synchronize()

let username = prefs.string(forKey: "username")

let booksInList = prefs.integer(forKey: "booksInList")

 

16. core data (example code)

import CoreData
class ViewController: UIViewController, UITableViewDelegate,
UITableViewDataSource {
var managedObjectContext: NSManagedObjectContext! //managed object context
 
func tableView(_ tableView: UITableView, numberOfRowsInSection section:
Int) -> Int{return }
 
override func viewDidLoad(){
let appDelegate: AppDelegate = UIApplication.shared.delegate as!
AppDelegate
managedObjectContext = appDelegate.persistentContainer.viewContext as NSManagedObjectContext
//将contextObject 链接到appDelegate
}
 
func loadBooks() -> [Book] {
 let fetchRequest: NSFetchRequest<Book> = Book.fetchRequest()
 var result: [Book] = []
 do {
 result = try managedObjectContext.fetch(fetchRequest)
 } catch {
 NSLog("My Error: %@", error as NSError)
 }
 return result
}
 
func tableView(_ tableView: UITableView, numberOfRowsInSection section:
Int) -> Int {
 return loadBooks().count
 }func tableView(_ tableView: UITableView, cellForRowAt indexPath:
IndexPath) -> UITableViewCell {
 guard let cell = tableView.dequeueReusableCell(withIdentifier:
"Cell") else { return UITableViewCell() }
 let book: Book = loadBooks()[indexPath.row]
 cell.textLabel?.text = book.title
 return cell
}
 
@IBAction func addNew(_ sender: Any) {
 let book: Book = NSEntityDescription.
insertNewObject(forEntityName: "Book", into:
managedObjectContext) as! Book
 book.title = "My Book" + String(loadBooks().count)
 do {
 try managedObjectContext.save()
 } catch let error as NSError {
 NSLog("My Error: %@", error)
 }
 myTableView.reloadData()
}
//根据实体名查询
let fetchRequest = NSFetchRequest(entityName: "People")
//设置查询条件
let predicate = NSPredicate(format:"id=1 and / or / not name='xx'")
fetchRequest.predicate=predicate

　 do {

　　　　let peopleList = try context.executeFetchRequest(fetchRequest)as! [NSManagedObject]

　　  for person in peopleListas! [People] {
　　　　　　print("查询到的人是\(person.name!)")
　　　　　　//修改操作:将查询到的结果修改后，再调用context.save()保存即可
　　　　　　if (person.name =="小红"){
　　　　　　　　 person.name="小花"
　　　　　　}
　　　　　　 //删除操作:将查询到的额结果删除后，再调用context.save()保存即可
　　　　　　if (person.name =="小明"){
　　　　　　　　context.deleteObject(person)
　　　　　　}
　　　　}
　　　　}catchlet error{

print("context can't fetch!, Error:\(error)")

}

do {

try context.save()

print("保存成功")

}catch let error{

print("context can't save!, Error:\(error)")

}

CoreData 多表

多表查询： https://blog.csdn.net/fengsh998/article/details/8123392?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.nonecase&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.nonecase

多条件查询：

https://blog.csdn.net/qq_29892943/article/details/52765344?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.nonecase&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.nonecase

CoreData中实体关联关系有三种，一对一，一对多，多对多，举一个简单的例子Accoun和Order之间关系.一个账户有多个订单

图中的RelationShip有三个字段，关联关系的名称，对应的Destination目标表的名字，Inverse表示反向关系，如果没有就是No Inverse.苹果关系建议是为了保证数据之间的一致性，最好设置反向关系.每个Order对应单一的用

户.

 

 

 

设置关联之后还需要设置对应的删除规则(Delete Rule)，苹果默认的关联规则是Nullify:

 

 

Deny 关系的Destination中只要有一个对象，就不能删除，如果账户还有订单，就不能删除账户

Nullify 只在逆向关系Optional的时候有效,Accout 删除之后，所有的Order中的account信息设置为nil

Cascade 删除对象后，删除destination所有对象.Account删除之后，会删除所有对应的Order对象.

NoAction 删除对象后，对Destination不做任何操作,在Destination中有大量对象的时候有用

设置关联关系，新建立一个订单，设置Order的关联对象是Account:

do {
 
            let account:Account = Account.findAccountByName(name: "FlyElephant")!
 
            let privateContext:NSManagedObjectContext = try CoreDataManager.sharedManager.newPrivateQueueContextWithNewPSC()
 
            let order:Order = NSEntityDescription.insertNewObject(forEntityName: "Order", into: privateContext) as! Order
            order.orderName = "台湾小零食--\(1)"
            order.orderNumber = Int32(100)
 
            order.account = account
 
            if privateContext.hasChanges {
                do {
                    print("保存成功")
                    try privateContext.save()
                } catch {
                    let nserror = error as NSError
                    fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
                }
            }
        }  catch {
            print(error)
        }

Account和Order不在同一个Context上下文中，会出现错误，可以在同一个上下文中进行实体对象查询

static func findAccountByName(name:String) -> Account? {
 
        let context:NSManagedObjectContext = CoreDataManager.sharedManager.mainQueueContext
 
        let fetchRequest:NSFetchRequest<NSFetchRequestResult> = NSFetchRequest(entityName: "Account")
 
        let predicate = NSPredicate.init(format: " accountName = %@", name)
        fetchRequest.predicate = predicate
 
        do {
            let searchResults = try context.fetch(fetchRequest)
            if searchResults.count >  {
                let account:Account = searchResults[] as! Account
                return account
            } else {
                return nil
            }
        } catch  {
            print(error)
        }
 
        return nil
    }

do {
 
            let account:Account = Account.findAccountByName(name: "FlyElephant")!
 
            let privateContext:NSManagedObjectContext = try CoreDataManager.sharedManager.newPrivateQueueContextWithNewPSC()
 
            let order:Order = NSEntityDescription.insertNewObject(forEntityName: "Order", into: privateContext) as! Order
            order.orderName = "FlyElephant-台湾小零食--\(1)"
            order.orderNumber = Int32()
 
            let accountInContext:Account = privateContext.object(with: account.objectID) as! Account
            order.account = accountInContext
 
            if privateContext.hasChanges {
                do {
                    print("保存成功")
                    try privateContext.save()
                } catch {
                    let nserror = error as NSError
                    fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
                }
            }
        }  catch {
            print(error)
        }

占位符：
NSPredicate *preTemplate = [NSPredicate predicateWithFormat:@"name==$NAME"];
NSDictionary *dic=[NSDictionary dictionaryWithObjectsAndKeys:
@"Name1", @"NAME",nil];
NSPredicate *pre=[preTemplate predicateWithSubstitutionVariables: dic];

分页查询

NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"RSSEntryModel" inManagedObjectContext:_managedObjectContext];
[request setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"articleDate" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[request setFetchLimit:21];
[request setFetchOffset:_currentPage * 21];
NSArray *rssTemp = [_managedObjectContext executeFetchRequest:request error:&error];

17  Protocols and Delegates

Protocol Definition
protocol RandomNumberGenerator {
 var mustBeSettable: Int { get set }
 var doesNotNeedToBeSettable: Int { get }
 func random() -> Double
}

 import UIKit
 // protocol used to send data back to the home view controller's
userDidFinish
protocol GuessDelegate {
func userDidFinish(_ controller:GuessInputViewController, guess:
String)
}
class GuessInputViewController: UIViewController {
 var delegate: GuessDelegate?
 var previousGuess: String = ""
 
 @IBOutlet weak var guessLabel: UILabel!
 @IBOutlet weak var guessTextField: UITextField!
 
 override func viewDidLoad() {
 super.viewDidLoad()
 
 // Do any additional setup after loading the view.
 if(!previousGuess.isEmpty) {
 guessLabel.text = "Your previous guess was \(previousGuess)"
 }
 guessTextField.becomeFirstResponder()
 }
@IBAction func saveGuess(_ sender: AnyObject) {
if let delegate = delegate, let guessText = guessTextField.text {
delegate.userDidFinish(self, guess: guessText)
}
}
}

protocol  XXXDelegate{ func methodA(data)}

classA{

var objectA: XXXDelegate? = nil

objectA.methodA(data)

}

classB : XXXDelegate{

func methodA(data){}

}

这样就实现了两个Controller之间的数据传递