iOS / Objective-C相當於Android的AsyncTask


Answers

iOS中沒有類,但可以使用隊列來模擬它。 你可以打電話給:

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    //Your code to execute in background...
});

異步任務和異步代碼調用下一個隊列在視圖中執行某些操作...:

dispatch_async(dispatch_get_main_queue(), ^{
    //Your code to execute on UIthread (main thread)
});

然後,使用這兩個隊列可以創建一個asyncTask類,將這個類添加到您的項目中以實現它們:

//
//  AsyncTask.h
//
//  Created by Mansour Boutarbouch Mhaimeur on 25/10/13.
//

#import <Foundation/Foundation.h>

@interface AsyncTask : NSObject

- (void) executeParameters: (NSArray *) params;
- (void) preExecute;
- (NSInteger) doInBackground: (NSArray *) parameters;
- (void) postExecute: (NSInteger) result;
@end
//
//  AsyncTask.m
//
//  Created by Mansour Boutarbouch Mhaimeur on 25/10/13.
//

#import "AsyncTask.h"

@implementation AsyncTask

- (void) executeParameters: (NSArray *) params{
    [self preExecute];
    __block NSInteger result;
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        result = [self doInBackground:params];
        dispatch_async(dispatch_get_main_queue(), ^{
            [self postExecute:result];
        });
    });
}

- (void) preExecute{
    //Method to override
    //Run on main thread (UIThread)
}

- (NSInteger) doInBackground: (NSArray *) parameters{
    //Method to override
    //Run on async thread (Background)
    return 0;
}

- (void) postExecute: (NSInteger) result{
    //Method to override
    //Run on main thread (UIThread)
}

@end

這是我在項目中使用的示例:

#import "AsyncTask.h"
#import "Chat.h"

@interface SendChatTask : AsyncTask{
    NSArray * chatsNotSent;
}

@end
#import "SendChatTask.h"

@implementation SendChatTask

- (void) preExecute{
    //Method to override
}

- (NSInteger) doInBackground: (NSArray *) parameters{
    //Method to override
    NSString *sendChatsURL = [NSString stringWithFormat:@"%@%@%@",HOST, NAMESPACE,URL_SEND_CHAT];
    chatsNotSent = [parameters objectAtIndex:0];

    NSString *response;
    NSMutableDictionary *params = [[NSMutableDictionary alloc] init];
    //...
    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:[ChatJSONParser wrapChatArray: chatsNotSent] options:0 error:&error];
    NSString *JSONString = [[NSString alloc] initWithBytes:[jsonData bytes] length:[jsonData length] encoding:NSUTF8StringEncoding];

    [params setObject:JSONString forKey:@"chats"];

    response = [HTTPClient executePOST:sendChatsURL parameters:params];

    if([respuesta isEqualToString:@"true"]){
        return 1;
    }else{
        return -1;
    }
}

- (void) postExecute: (NSInteger) result{
    //Method to override
    if (result == 1) {
        for (Chat *chat in chatsNotSent) {
            chat.state = STATE_NOT_SENT;
            [chat save];
            AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
            [appDelegate refreshChat];
        }
    } else {

    }
}

@end

接下來的電話:

[[[SendChatTask alloc] init] executeParameters:[NSArray arrayWithObjects: chatsNotSent, nil]];

您可以添加一個publishProgress()更新方法和相應的...我暫時不使用它,因為我在後台服務中調用了我的異步任務。

我希望這有幫助。

Question

我熟悉在Android中使用AsyncTask :創建子類,在子類的實例上調用execute ,並在UI線程或主線程上調用onPostExecuteiOS中有什麼等價物?




斯威夫特3

在Android中,當我想在後台線程上運行任務並在完成後更新UI時,我使用了AsyncTask示例 )。 現在,當我製作我的應用的iOS版本時,我使用Grand Central Dispatch (GCD)來做同樣的事情。 以下是Swift如何完成的:

DispatchQueue.global(qos: .background).async {

    // code to be run on a background task

    DispatchQueue.main.async {

        // code to be run on the main thread after the background task is finished
    }
}

筆記