Fire methods step by step

Question

Hi how can I fire functions and methods in a queue in Objective C ? I mean something like this :

method 1 then method 2 then method 3 , Should I use NSThread ?

Answer 1

One way is to have a Queue or Stack of function pointers, then execute and pop the topmost method until no methods are left. Obviously, you can do this with an array and a currentIndex variable as well (increment currentIndex from 0 to arraySize - 1, executing the function pointer at myArray[currentIndex] each time). See Function Pointers in Objective C for more details on the function pointers themselves.

Answer 2

I have a different solution that involved in using GCD Serial Queues and NSSelectorFromString method.

1st: Create an array with your methods names

2nd: Create a GCD Serial Queue

3rd: Using NSSelectorFromString to convert method name string to method and insert it into the serial Q using the a for loop, etc.

Here is the complete tested code:

- (IBAction)buttonSerialQPressed:(id)sender 
{
    dispatch_queue_t serialdQueue;
    serialdQueue = dispatch_queue_create("com.mydomain.testbed.serialQ", NULL);

    NSArray *arrayMethods = [NSArray arrayWithObjects:@"method1", @"method2", @"method3", nil];
    for (NSString *methodName in arrayMethods) 
    {
        dispatch_async(serialdQueue, ^{
            SEL myMethod = NSSelectorFromString(methodName);
            [self performSelector:myMethod];
        });
    }
}

-(void)method1
{
    for (int i=0; i<1000; i++) 
    {
        NSLog(@"method1 i: %i", i);
    }
}

-(void)method2
{
    for (int i=0; i<10; i++) 
    {
        NSLog(@"method2 i: %i", i);
    }
}

-(void)method3
{
    for (int i=0; i<100; i++) 
    {
        NSLog(@"method3 i: %i", i);
    }
}

Answer 3

I would use NSOperationQueue. You can set it run one operation at a time, in which case it will proceed step by step through the method calls you want. You can use NSInvocationOperation to create operations out of method calls.