How to get notified when enumerateLinesUsingBlock is completed - ios

Question

Is there any way to notify when a enumerateLinesUsingBlock is completed? Please check below code. I am calling createFastSearchData method with chunk by chunk data in a while loop and inside that taking each lines and processing it. In while condition I am checking the length of the main string and I want to continue untill it completes the total length. So I want to make sure that enumerateLinesUsingBlock is completed before the while loop trigger again.
while(<checking the length of the mainstring>){
[self createFastSearchData:string];
}
- (void)createFastSearchData:(NSString *)newChunk{
[newChunk enumerateLinesUsingBlock:^(NSString * line, BOOL * stop)
{}];
}
Added:
I am working with blocks and finding difficulty to understand the actual flow. Please check the below code. I want to call fetchCSVData method by passing different values in an array filesToBeFetchedWhat. I want to make sure that, fetchCSVData should not overlap. How can I do that? Please help
dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
#autoreleasepool {
for (int i = 0; i < filesToBeFetched.count; i++) {
[applicationDelegate fetchCSVData:[filesToBeFetched objectAtIndex:i]];
}
}
dispatch_async( dispatch_get_main_queue(), ^{
NSLog(#"Fetching is done *********************");
});
});

Answer 1

To answer the first part of the question:
All enumerate...UsingBlock methods don't work asynchronously.
Regarding the added part:
Assuming fetchCSVData works also synchronously, that's the preferred way to process the data
dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
#autoreleasepool {
for (int i = 0; i < filesToBeFetched.count; i++) {
[applicationDelegate fetchCSVData:[filesToBeFetched objectAtIndex:i]];
dispatch_async( dispatch_get_main_queue(), ^{
NSLog(#"Fetching is done *********************");
});
}
}
});