Operation example

OperationExample.m

@interface MyAsyncOperation ()
@property (nonatomic) BOOL isExecuting;
@property (nonatomic) BOOL isFinished;
@end

@implementation MyAsyncOperation 

- (void)start {
    self.isFinished = NO;
    self.isExecuting = YES;
    
    [self loadAsyncStuffWithCompletion:^{
        self.isExecuting = NO;
        self.isFinished = YES;
    }];
}

- (BOOL)isConcurrent {
    return YES;
}

- (void)setIsExecuting:(BOOL)isExecuting {
    [self willChangeValueForKey:@"isExecuting"];
    _isExecuting = isExecuting;
    [self didChangeValueForKey:@"isExecuting"];
}

- (void)setIsFinished:(BOOL)isFinished {
    [self willChangeValueForKey:@"isFinished"];
    _isFinished = isFinished;
    [self didChangeValueForKey:@"isFinished"];
}

@end