swift 下拉图片变大 coreData 声明数组变量

最新推荐文章于 2024-09-06 14:11:39 发布

原创最新推荐文章于 2024-09-06 14:11:39 发布 · 678 阅读

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本文介绍了一个使用SwiftUI实现的新闻应用案例，演示了如何声明数组变量存储新闻数据，利用Core Data进行数据持久化管理，并实现了下拉刷新时图片平滑放大的效果以及单元格渐显动画。

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1 声明数组变量
（1）
import Foundation
import UIKit

struct News {
var newsTitle: String
var newsCategory: String
}
（2）var newsArray = News
（3）
let news7 = News(newsTitle: “Eclipse mints release new Blackcurrent flavor”, newsCategory: “World”)
let news8 = News(newsTitle: “Aetna and Humana close to multi-billion dollar deal”, newsCategory: “Finance”)
newsArray = [news1, news2, news3, news4, news5, news6, news7, news8]

2 coreData
func applicationWillTerminate(application: UIApplication) {
self.saveContext()
}

// MARK: - Core Data stack

lazy var applicationDocumentsDirectory: NSURL = {
    let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
    return urls[urls.count-1] as! NSURL
}()

lazy var managedObjectModel: NSManagedObjectModel = {
    let modelURL = NSBundle.mainBundle().URLForResource("Yahoo_News_Digest_Replicate", withExtension: "momd")!
    return NSManagedObjectModel(contentsOfURL: modelURL)!
}()

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
    var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("Yahoo_News_Digest_Replicate.sqlite")
    var error: NSError? = nil
    var failureReason = "There was an error creating or loading the application's saved data."
    if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {
        coordinator = nil
        // Report any error we got.
        var dict = [String: AnyObject]()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason
        dict[NSUnderlyingErrorKey] = error
        error = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
        NSLog("Unresolved error \(error), \(error!.userInfo)")
        abort() // 断言
    }

    return coordinator
}()

lazy var managedObjectContext: NSManagedObjectContext? = {
    let coordinator = self.persistentStoreCoordinator
    if coordinator == nil {
        return nil
    }
    var managedObjectContext = NSManagedObjectContext()
    managedObjectContext.persistentStoreCoordinator = coordinator
    return managedObjectContext
}()

// MARK: - Core Data Saving support

func saveContext () {
    if let moc = self.managedObjectContext {
        var error: NSError? = nil
        if moc.hasChanges && !moc.save(&error) {
            NSLog("Unresolved error \(error), \(error!.userInfo)")
            abort()
        }
    }
}

3 下拉图片变大

func updatingTableHeaderView() {
    var newsHeaderTableRect = CGRect(x: 0, y: -kTableHeightHeader, width: self.view.frame.size.width, height: kTableHeightHeader)

    if self.newsTableView.contentOffset.y < -kTableHeightHeader {
        newsHeaderTableRect.origin.y = self.newsTableView.contentOffset.y
        newsHeaderTableRect.size.height = -self.newsTableView.contentOffset.y
    }

    self.tableHeaderView.frame = newsHeaderTableRect

    visiblePortionOfNewsTableHeader(newsHeaderTableRect: newsHeaderTableRect)
}

func visiblePortionOfNewsTableHeader(#newsHeaderTableRect: CGRect) {

    self.tableHeaderMaskToBeVisible = CAShapeLayer()
    self.tableHeaderMaskToBeVisible.fillColor = UIColor.blackColor().CGColor
    self.tableHeaderView.layer.mask = self.tableHeaderMaskToBeVisible

    let trapeziumHeaderMask = UIBezierPath()
    trapeziumHeaderMask.moveToPoint(CGPointMake(0, 0))
    trapeziumHeaderMask.addLineToPoint(CGPointMake(newsHeaderTableRect.width, 0))
    trapeziumHeaderMask.addLineToPoint(CGPointMake(newsHeaderTableRect.width, newsHeaderTableRect.height))
    trapeziumHeaderMask.addLineToPoint(CGPointMake(0, newsHeaderTableRect.height - kTableToBeCutOff))
    self.tableHeaderMaskToBeVisible.path = trapeziumHeaderMask.CGPath
}

4 cell 渐变的出现
func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {

    if self.arrayCheckCellHasLoaded[indexPath.row] == false {
        cell.alpha = 0

        UIView.animateWithDuration(1, animations: { () -> Void in
            cell.alpha = 1

        });
        self.arrayCheckCellHasLoaded[indexPath.row] = true
    }
}