CODEWITHSUNDEEP
iosobjective-cnsstringnsarrayblock
Andrew
Andrew

Reputation: 7883

Loop through block while waiting for previous execution to finish

I have a block of code which loops through an array and performs block code on it. Currently it looks like this:

for (NSString *myString in myArray) {

    [self doSomethingToString:myString WithCompletion:^(BOOL completion) {
        string = [NSString stringByAppendingString:@"Test"];
    }];

}

I want to wait for the previous iteration to finish before I start on the next one. How can I loop through some block code like this?

Upvotes: 5

Views: 2364

Answers (3)

Benoît
Benoît

Reputation: 13

Swift 3.1 

var sema = DispatchSemaphore(value: 0)
for myString: String in myArray {
    doSomething(to: myString, withCompletion: {(_ completion: Bool) -> Void in
        string = String + ("Test")
        dispatch_semaphore_signal(sema)
    })
    dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER)
    dispatch_release(sema)
}

Upvotes: 0

Chamira Fernando
Chamira Fernando

Reputation: 6846

Try this

    dispatch_semaphore_t sema = dispatch_semaphore_create(0);

    for (NSString *myString in myArray) {

        [self doSomethingToString:myString WithCompletion:^(BOOL completion) {
            string = [NSString stringByAppendingString:@"Test"];
            dispatch_semaphore_signal(sema);
        }];

        dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
        dispatch_release(sema);

    }

Upvotes: 9

Suhit Patil
Suhit Patil

Reputation: 12023

you can use

[myArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop){
   string = [NSString stringByAppendingString:@"Test"];
}];

Upvotes: 0

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