我刚刚升级到Xcode 4.5 GM，发现你现在可以将“4英寸视网膜”大小应用到故事板中的视图控制器上。

现在，如果我想创建一个同时在iPhone 4和5上运行的应用程序，当然我必须构建每个窗口两次，但我还必须检测用户的iPhone屏幕是3.5英寸还是4英寸，然后应用视图。

我该怎么做呢?

我有一个UITableView在iOS 8下运行，我在故事板中使用约束的自动单元格高度。

我的一个单元格包含一个UITextView，我需要它根据用户输入收缩和展开-点击收缩/展开文本。

我通过在文本视图中添加一个运行时约束，并在响应用户事件时改变约束上的常数来做到这一点:

-(void)collapse:(BOOL)collapse; {

    _collapsed = collapse;

    if(collapse)
        [_collapsedtextHeightConstraint setConstant: kCollapsedHeight]; // 70.0
    else
        [_collapsedtextHeightConstraint setConstant: [self idealCellHeightToShowFullText]];

    [self setNeedsUpdateConstraints];

}

无论何时我这样做，我包装在tableView更新和调用[tableView setNeedsUpdateConstraints]:

[tableView beginUpdates];

[_briefCell collapse:!_showFullBriefText];

[tableView setNeedsUpdateConstraints];
// I have also tried 
// [self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationTop];
// with exactly the same results.

[tableView endUpdates];

当我这样做的时候，我的单元格确实会扩展(并在做的时候动画)，但我得到一个约束警告:

2014-07-31 13:29:51.792 OneFlatEarth[5505:730175] Unable to simultaneously satisfy constraints.

Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 

(

    "<NSLayoutConstraint:0x7f94dced2b60 V:[UITextView:0x7f94d9b2b200'Brief text: Lorem Ipsum i...'(388)]>",

    "<NSLayoutConstraint:0x7f94dced2260 V:[UITextView:0x7f94d9b2b200'Brief text: Lorem Ipsum i...']-(15)-|   (Names: '|':UITableViewCellContentView:0x7f94de5773a0 )>",

    "<NSLayoutConstraint:0x7f94dced2350 V:|-(6)-[UITextView:0x7f94d9b2b200'Brief text: Lorem Ipsum i...']   (Names: '|':UITableViewCellContentView:0x7f94de5773a0 )>",

    "<NSLayoutConstraint:0x7f94dced6480 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x7f94de5773a0(91)]>"
 )

Will attempt to recover by breaking constraint 

<NSLayoutConstraint:0x7f94dced2b60 V:[UITextView:0x7f94d9b2b200'Brief text: Lorem Ipsum i...'(388)]>

388是我计算的高度，UITextView上的其他约束是我从Xcode/IB中得到的。

最后一个是困扰我-我猜uiview - encapsulation - layout - height是计算单元格的高度时，它是第一次渲染-(我设置我的UITextView高度>= 70.0)，但它似乎不正确，这个派生约束然后驳回更新用户cnstraint。

更糟糕的是，尽管布局代码说它试图打破我的高度限制，但它并没有-它继续重新计算单元格的高度，一切都按照我想要的方式绘制。

所以，什么是NSLayoutConstraint UIView-Encapsulated-Layout-Height(我猜它是计算的高度自动单元格大小)，我应该如何去迫使它重新计算干净?

我尝试了一遍又一遍地生成一个。pem文件，每次都从客户端帐户生成证书，然后使用终端生成。pem文件，但这没有用。谁能给出一个循序渐进的步骤?

我一直在研究一种方法，在多个设备(如iPad或Mac)之间同步存储在iPhone应用程序中的核心数据。在iOS上，用于core data的同步框架并不多(如果有的话)。然而，我一直在思考以下概念:

A change is made to the local core data store, and the change is saved. (a) If the device is online, it tries to send the changeset to the server, including the device ID of the device which sent the changeset. (b) If the changeset does not reach the server, or if the device is not online, the app will add the change set to a queue to send when it does come online. The server, sitting in the cloud, merges the specific change sets it receives with its master database. After a change set (or a queue of change sets) is merged on the cloud server, the server pushes all of those change sets to the other devices registered with the server using some sort of polling system. (I thought to use Apple's Push services, but apparently according to the comments this is not a workable system.)

有什么特别的需要我考虑的吗?我已经研究了REST框架，如ObjectiveResource、Core Resource和RestfulCoreData。当然，这些都是与Ruby on Rails一起工作的，我并不依赖于Ruby on Rails，但这是一个起点。我的解决方案的主要要求是:

任何更改都应该在后台发送，而不需要暂停主线程。 它应该使用尽可能少的带宽。

我想过一些挑战:

Making sure that the object IDs for the different data stores on different devices are attached on the server. That is to say, I will have a table of object IDs and device IDs, which are tied via a reference to the object stored in the database. I will have a record (DatabaseId [unique to this table], ObjectId [unique to the item in the whole database], Datafield1, Datafield2), the ObjectId field will reference another table, AllObjects: (ObjectId, DeviceId, DeviceObjectId). Then, when the device pushes up a change set, it will pass along the device Id and the objectId from the core data object in the local data store. Then my cloud server will check against the objectId and device Id in the AllObjects table, and find the record to change in the initial table. All changes should be timestamped, so that they can be merged. The device will have to poll the server, without using up too much battery. The local devices will also need to update anything held in memory if/when changes are received from the server.

我还遗漏了什么吗?我应该考虑什么样的框架来实现这一点?

当我试着在我的iPhone上检查网络连接时，我得到了一堆错误。有人能帮我解决这个问题吗?

代码:

import Foundation
import SystemConfiguration

public class Reachability {

class func isConnectedToNetwork() -> Bool {

    var zeroAddress = sockaddr_in()
    zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
    zeroAddress.sin_family = sa_family_t(AF_INET)

    let defaultRouteReachability = withUnsafePointer(&zeroAddress) {
        SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0))
    }

    var flags: SCNetworkReachabilityFlags = 0

    if SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) == 0 {
        return false
    }

    let isReachable = (flags & UInt32(kSCNetworkFlagsReachable)) != 0
    let needsConnection = (flags & UInt32(kSCNetworkFlagsConnectionRequired)) != 0

    return (isReachable && !needsConnection) ? true : false
}

}

代码的错误:

如果它是不可读的，错误1说:

'Int'不能转换为'SCNetworkReachabilityFlags'

错误2和3:

找不到一个超载的'init'接受提供的参数

我试图在我的IOS项目中添加一个框架，但当我构建时，我总是得到相同的消息:

ld:框架没有找到Pods Clang:错误:连接器命令失败，退出码为1(使用-v查看调用)

我试图删除我的pod目录，然后运行pod install 我打开。xcworkspace，就像它在pod安装的日志中写的那样，我在xcode上清理项目，然后尝试构建，但它不会工作。

我的podfile是这样的:

xcodeproj '/Users/guillaume/project/Mobile/iOS/FoodPin/FoodPin.xcodeproj'
source 'https://github.com/CocoaPods/Specs.git'
platform :ios, '8.0'
use_frameworks!
pod 'SwiftHTTP', '~> 0.9.2'

我的xcode版本是6.3.1

谢谢你！

尝试用swift字典中的键字符串填充数组。

var componentArray: [String]

let dict = NSDictionary(contentsOfFile: NSBundle.mainBundle().pathForResource("Components", ofType: "plist")!)
componentArray = dict.allKeys

这将返回一个错误:'AnyObject'与string不相同

也试过

componentArray = dict.allKeys as String 

but get: 'String'不能转换为[String]

我目前正在用Xcode 6 (Beta 6)测试我的应用程序。UIActivityViewController在iPhone设备和模拟器上工作得很好，但在iPad模拟器和设备(iOS 8)上崩溃

Terminating app due to uncaught exception 'NSGenericException', 
reason: 'UIPopoverPresentationController 
(<_UIAlertControllerActionSheetRegularPresentationController: 0x7fc7a874bd90>) 
should have a non-nil sourceView or barButtonItem set before the presentation occurs.

我使用以下代码用于iPhone和iPad的iOS 7以及iOS 8

NSData *myData = [NSData dataWithContentsOfFile:_filename];
NSArray *activityItems = [NSArray arrayWithObjects:myData, nil];
UIActivityViewController *activityViewController = [[UIActivityViewController alloc] initWithActivityItems:nil applicationActivities:nil];
activityViewController.excludedActivityTypes = @[UIActivityTypeCopyToPasteboard];
[self presentViewController:activityViewController animated:YES completion:nil];

我得到一个类似的崩溃在我的另一个应用程序以及。你能引导我吗?ios8中的UIActivityViewController有什么变化吗?我查过了，但在这上面什么也没找到

我正在使用swift构建一个RSS阅读器，需要实现重新加载功能。

以下是我如何努力做到这一点。

class FirstViewController: UIViewController,
    UITableViewDelegate, UITableViewDataSource {

   @IBOutlet var refresh: UIScreenEdgePanGestureRecognizer
   @IBOutlet var newsCollect: UITableView

   var activityIndicator:UIActivityIndicatorView? = nil

   override func viewDidLoad() {
       super.viewDidLoad()
       self.newsCollect.scrollEnabled = true
      // Do any additional setup after loading the view, typically from a nib.

      if nCollect.news.count <= 2{
          self.collectNews()
       }
      else{
          self.removeActivityIndicator()
       }
      view.addGestureRecognizer(refresh)
   }



@IBAction func reload(sender: UIScreenEdgePanGestureRecognizer) {
    nCollect.news = News[]()
    return newsCollect.reloadData()
}

我得到:

财产的自我。刷新'未在super初始化。init调用

请帮助我理解手势识别器的行为。一个工作样例代码将是一个很大的帮助。

谢谢。

我有以下简单的代码连接到SSL网页

NSMutableURLRequest *urlRequest=[NSMutableURLRequest requestWithURL:url];
[ NSURLConnection sendSynchronousRequest: urlRequest returningResponse: nil error: &error ];

除非它给出一个错误，如果证书是自签名的一个错误域=NSURLErrorDomain Code=-1202 UserInfo=0xd29930“不受信任的服务器证书”。有没有一种方法来设置它接受连接(就像在浏览器中你可以按accept)或一种方法来绕过它?