UIAlertView / UIAlertController兼容iOS 7和iOS 8

时间：2014-08-04 02:26:45

标签： ios swift uialertview uialertcontroller

我正在使用Swift编写应用程序，我需要显示警报。该应用必须兼容iOS 7和iOS 8。由于UIAlertView已替换为UIAlertController，如何在不检查系统版本的情况下检查UIAlertController是否可用？我听说Apple建议我们不要检查设备的系统版本，以确定API的可用性。

这就是我在iOS 8中使用的内容，但在iOS 7上使用“dyld: Symbol not found: _OBJC_CLASS_$_UIAlertAction”崩溃：

let alert = UIAlertController(title: "Error", message: message, preferredStyle: .Alert)
let cancelAction = UIAlertAction(title: "OK", style: .Cancel, handler: nil)
alert.addAction(cancelAction)
presentViewController(alert, animated: true, completion: nil)

如果我使用UIAlertView for iOS 8，我会收到此警告：Warning: Attempt to dismiss from view controller <_UIAlertShimPresentingViewController: 0x7bf72d60> while a presentation or dismiss is in progress!

14 个答案:

答案 0 :(得分：76)

检测模式与Objective-C风格相同。

您需要检测当前活动运行时是否能够实例化此类

if objc_getClass("UIAlertController") != nil {

     println("UIAlertController can be instantiated")

      //make and use a UIAlertController

 }
 else {

      println("UIAlertController can NOT be instantiated")

      //make and use a UIAlertView
}

请勿尝试根据操作系统版本来解决此问题。您需要检测能力不操作系统。

编辑

此答案NSClassFromString("UIAlertController")的原始检测器在-O优化下失败，因此已将其更改为适用于发布版本的当前版本

编辑2

NSClassFromString正在Xcode 6.3 / Swift 1.2的所有优化中工作

答案 1 :(得分：29)

对于非swift代码，纯Objective-C执行此操作

if ([UIAlertController class])
    {
        // use UIAlertController
        UIAlertController *alert= [UIAlertController
                                      alertControllerWithTitle:@"Enter Folder Name"
                                      message:@"Keep it short and sweet"
                                      preferredStyle:UIAlertControllerStyleAlert];

        UIAlertAction* ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
                                                   handler:^(UIAlertAction * action){
                                                       //Do Some action here
                                                       UITextField *textField = alert.textFields[0];
                                                       NSLog(@"text was %@", textField.text);

                                                   }];
        UIAlertAction* cancel = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault
                                                       handler:^(UIAlertAction * action) {

                                                           NSLog(@"cancel btn");

                                                           [alert dismissViewControllerAnimated:YES completion:nil];

                                                       }];

        [alert addAction:ok];
        [alert addAction:cancel];

        [alert addTextFieldWithConfigurationHandler:^(UITextField *textField) {
            textField.placeholder = @"folder name";
            textField.keyboardType = UIKeyboardTypeDefault;
        }];

        [self presentViewController:alert animated:YES completion:nil];

    }
    else
    {
        // use UIAlertView
        UIAlertView* dialog = [[UIAlertView alloc] initWithTitle:@"Enter Folder Name"
                                                         message:@"Keep it short and sweet"
                                                        delegate:self
                                               cancelButtonTitle:@"Cancel"
                                               otherButtonTitles:@"OK", nil];

        dialog.alertViewStyle = UIAlertViewStylePlainTextInput;
        dialog.tag = 400;
        [dialog show];

    }

答案 2 :(得分：9)

我很生气，我不得不写出两种情况，所以我写了一个兼容的UIAlertController，适用于iOS 7，所以我把它扔在GitHub上。我尽力复制（更好）添加UIAlertController的按钮和动作的方法。适用于Objective-C和Swift。我正在发布这个，因为我在Google上搜索时发现了这个问题，并认为这对其他人有帮助。

https://github.com/BayPhillips/compatible-alert-controller

答案 3 :(得分：8)

您可以使用以下代码解决问题： - 

var device : UIDevice = UIDevice.currentDevice()!;
        var systemVersion = device.systemVersion;
        var iosVerion : Float = systemVersion.bridgeToObjectiveC().floatValue;
        if(iosVerion < 8.0) {
            let alert = UIAlertView()
            alert.title = "Noop"
            alert.message = "Nothing to verify"
            alert.addButtonWithTitle("Click")
            alert.show()
        }else{
            var alert : UIAlertController = UIAlertController(title: "Noop", message: "Nothing to verify", preferredStyle: UIAlertControllerStyle.Alert)
            alert.addAction(UIAlertAction(title: "Click", style:.Default, handler: nil))
            self.presentViewController(alert, animated: true, completion: nil)
        }

和UIKit必须标记为Optional而不是Required。

Courtsey： - Alert that can work on iOS 7 and iOS 8

答案 4 :(得分：6)

Swift 2.0 

 if #available(iOS 8.0, *) {

 } else {

 }

答案 5 :(得分：4)

如果这是共享代码，并且代码可能在iOS 8扩展中使用（其中UIAlertView和UIActionSheet是受限制的API）以及iOS 7，其中UIAlertController不存在，请查看：JVAlertController

它是iOS 7的UIAlertController的API兼容后端，我承诺使SDK代码可以安全地用于iOS 7和iOS 8扩展。

答案 6 :(得分：2)

您可以使用类别来解决这个问题（尽管您需要将其转换为Swift）：

@implementation UIView( AlertCompatibility )

+( void )showSimpleAlertWithTitle:( NSString * )title
                          message:( NSString * )message
                cancelButtonTitle:( NSString * )cancelButtonTitle
{
    if( [[UIDevice currentDevice] isSystemVersionLowerThan: @"8"] )
    {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle: title
                                                        message: message
                                                       delegate: nil
                                              cancelButtonTitle: cancelButtonTitle
                                              otherButtonTitles: nil];
        [alert show];
    }
    else
    {
        // nil titles break alert interface on iOS 8.0, so we'll be using empty strings
        UIAlertController *alert = [UIAlertController alertControllerWithTitle: title == nil ? @"": title
                                                                       message: message
                                                                preferredStyle: UIAlertControllerStyleAlert];

        UIAlertAction *defaultAction = [UIAlertAction actionWithTitle: cancelButtonTitle
                                                                style: UIAlertActionStyleDefault
                                                              handler: nil];

        [alert addAction: defaultAction];

        UIViewController *rootViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
        [rootViewController presentViewController: alert animated: YES completion: nil];
    }
}

@end

@implementation UIDevice( SystemVersion )

-( BOOL )isSystemVersionLowerThan:( NSString * )versionToCompareWith
{
    if( versionToCompareWith.length == 0 )
        return NO;

    NSString *deviceSystemVersion = [self systemVersion];
    NSArray *systemVersionComponents = [deviceSystemVersion componentsSeparatedByString: @"."];

    uint16_t deviceMajor = 0;
    uint16_t deviceMinor = 0;
    uint16_t deviceBugfix = 0;

    NSUInteger nDeviceComponents = systemVersionComponents.count;
    if( nDeviceComponents > 0 )
        deviceMajor = [( NSString * )systemVersionComponents[0] intValue];
    if( nDeviceComponents > 1 )
        deviceMinor = [( NSString * )systemVersionComponents[1] intValue];
    if( nDeviceComponents > 2 )
        deviceBugfix = [( NSString * )systemVersionComponents[2] intValue];


    NSArray *versionToCompareWithComponents = [versionToCompareWith componentsSeparatedByString: @"."];

    uint16_t versionToCompareWithMajor = 0;
    uint16_t versionToCompareWithMinor = 0;
    uint16_t versionToCompareWithBugfix = 0;

    NSUInteger nVersionToCompareWithComponents = versionToCompareWithComponents.count;
    if( nVersionToCompareWithComponents > 0 )
        versionToCompareWithMajor = [( NSString * )versionToCompareWithComponents[0] intValue];
    if( nVersionToCompareWithComponents > 1 )
        versionToCompareWithMinor = [( NSString * )versionToCompareWithComponents[1] intValue];
    if( nVersionToCompareWithComponents > 2 )
        versionToCompareWithBugfix = [( NSString * )versionToCompareWithComponents[2] intValue];

    return ( deviceMajor < versionToCompareWithMajor )
           || (( deviceMajor == versionToCompareWithMajor ) && ( deviceMinor < versionToCompareWithMinor ))
           || (( deviceMajor == versionToCompareWithMajor ) && ( deviceMinor == versionToCompareWithMinor ) && ( deviceBugfix < versionToCompareWithBugfix ));
}

@end

然后致电

[UIView showSimpleAlertWithTitle: @"Error" message: message cancelButtonTitle: @"OK"];

但是，如果您不想检查系统版本，请使用

BOOL lowerThaniOS8 = NSClassFromString( @"UIAlertController" ) == nil;

类别UIView（AlertCompatibility）

答案 7 :(得分：2)

如果您同时使用iOS 7-UIAlertView和iOS 8+ UIAlertController，并且您希望您的UIAlertController块调用您的UIAlertView的委托（例如MyController）alertView：didDismissWithButtonIndex方法继续处理结果，这里是一个示例怎么做：

if ([UIAlertController class]) {
    MyController * __weak mySelf = self;

    UIAlertController *alertController = [UIAlertController
        alertControllerWithTitle:alertTitle
        message:alertMessage
        preferredStyle:UIAlertControllerStyleAlert];

    UIAlertAction *cancelAction = [UIAlertAction
        actionWithTitle:alertCancel
        style:UIAlertActionStyleCancel
        handler:^(UIAlertAction *action)
            {
            [mySelf alertView:nil didDismissWithButtonIndex:0];
            }
    ];

...

这使用Apple的建议来捕获块中的 self ：Avoid Strong Reference Cycles when Capturing self

当然，此方法假设您在控制器中只有一个UIAlertView，因此将nil作为其值传递给委托方法。否则，您需要实例化（并标记）“假”UIAlertView以传递给alertView：didDismissWithButtonIndex。

答案 8 :(得分：1)

此处检查UIAlertView和UIAlertContoller的两种方式。

检查1： iOS版本检查UIAlertController类。 

    if #available(iOS 8.0, *) {

        // UIALertController
        let alert = UIAlertController(title: "Alert", message: "Alert after 8.0", preferredStyle: .Alert)
        let cancelAction = UIAlertAction(title: "OK", style: .Cancel, handler: nil)
        alert.addAction(cancelAction)
        presentViewController(alert, animated: true, completion: nil)
    } else {

        // UIALertView
        UIAlertView(title: "Alert", message: "Alert below iOS V 8.0", delegate: nil, cancelButtonTitle: "OK").show()
    }

检查2：检查UIAlertController无，然后检查iOS版本低于8.0。 

    if objc_getClass("UIAlertController") != nil {

        // UIALertController
        let alert = UIAlertController(title: "Alert", message: "Alert after 8.0", preferredStyle: .Alert)
        let cancelAction = UIAlertAction(title: "OK", style: .Cancel, handler: nil)
        alert.addAction(cancelAction)
        presentViewController(alert, animated: true, completion: nil)

    }
    else {

        // UIALertView
        UIAlertView(title: "Alert", message: "Alert below iOS V 8.0", delegate: nil, cancelButtonTitle: "OK").show()
    }

答案 9 :(得分：0)

如果您想与iOS 7兼容，请不要使用UIAlertController。就这么简单。

UIAlertView尚未被替换，它仍然完美无缺，并且在可预见的未来将继续完美运作。

答案 10 :(得分：0)

这是我的拖放快速解决方案：

//Alerts change in iOS8, this method is to cover iOS7 devices
func CozAlert(title: String, message: String, action: String, sender: UIViewController){

    if respondsToSelector("UIAlertController"){
        var alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: action, style: UIAlertActionStyle.Default, handler:nil))
        sender.presentViewController(alert, animated: true, completion: nil)
    }
    else {
        var alert = UIAlertView(title: title, message: message, delegate: sender, cancelButtonTitle:action)
        alert.show()
    }
}

这样打电话：

CozAlert("reportTitle", message: "reportText", action: "reportButton", sender: self)

请注意，这仅适用于最基本的警报，您可能需要其他高级内容代码。

答案 11 :(得分：-1)

尝试以下代码。它适用于iOS 8及以下版本。

if (IS_OS_8_OR_LATER) {
    UIAlertController *alertVC = [UIAlertController alertControllerWithTitle:title message:msg preferredStyle:UIAlertControllerStyleAlert];

    UIAlertAction *cancelAction = [UIAlertAction
                                 actionWithTitle:@"OK"
                                 style:UIAlertActionStyleCancel
                                 handler:^(UIAlertAction *action)
                                 {

                                 }];
    [alertVC addAction:cancelAction];

    [[[[[UIApplication sharedApplication] windows] objectAtIndex:0] rootViewController] presentViewController:alertVC animated:YES completion:^{

    }];
}
else{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title message:msg delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
    [alert show];
}

答案 12 :(得分：-2)

在iOS8中，有一个新类UIAlertController取代UIAlertView和UIActionSheet。从iOS8开始，使用UIAlertController，对于iOS8，然后使用UIAlertView和UIActionSheet。我认为iOS8添加size classes更改UIAlertView显示方向。请参阅：https://github.com/wangyangcc/FYAlertManage

答案 13 :(得分：-2)

从此link下载警报课程 并且可以轻松地用于ios 6,7和8 

//Old code  
**UIAlertView** *alert=[[**UIAlertView** alloc]initWithTitle:@"FreeWare" message:@"Welcome to Common class" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil];

//New code 

**MyAlertView** *alert=[[**MyAlertView** alloc]initWithTitle:@"FreeWare" message:@"Welcome to Common class" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil];
相关问题
最新问题