Different ways to execute a block property. This runs in CodeRunner. Replace one of the #ifdef X below with #ifdef YES, and comment person = nil;.

main.m

int main(int argc, const char *argv[]) 
{
    @autoreleasepool 
    {
        Person *person = [[Person alloc] initWithName:@"Alice"];
        [person execute:person.salute delay:1];
        person = nil;
        NSLog(@"nil'ed");

        for (int i=3; i>0; i--) {
            NSLog(@".");
            NSDate *oneSecond = [NSDate dateWithTimeIntervalSinceNow:1];
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:oneSecond];
        }

    }
}

Person.h

#import <Foundation/Foundation.h>
#undef X

typedef void (^salute_t)();

@interface Person : NSObject

@property (nonatomic,copy) NSString *name;
@property (nonatomic,copy) salute_t salute;

-(void) execute:(salute_t)salute delay:(long long)seconds;

@end

Person.m

@implementation Person

-(instancetype) initWithName:(NSString*)name {
    self = [super init];
    if (!self){
        return nil;
    }
    
    self.name = name;
    self.salute = ^{ NSLog(@"block undefined"); };

    #ifdef X
    // Runs, but creates a retain cycle.
    // #1 warning: capturing 'self' strongly in this block is likely to lead to a retain cycle
    // #2 note: block will be retained by an object strongly retained by the captured object
    /*2*/ self.salute = ^{ NSLog(@"%@", /*1*/ self->_name); };
    #endif
    
    #ifdef X
    // Compiler error.
    // #1 error: dereferencing a __weak pointer is not allowed due to possible null 
    //           value caused by race condition, assign it to strong variable first
    __block __weak Person *weakSelf = self;
    self.salute = ^{ NSLog(@"%@", /*1*/ weakSelf->_name); };
    #endif
    
    #ifdef X
    // This shows no warning, but it will dereference nil if the object is nil
    // by the time the block is running. Dereferencing nil produces a segmentation fault.
    __block __weak Person *weakSelf = self;
    self.salute = ^{
        __strong Person *strongSelf = weakSelf;
        NSLog(@"%@", strongSelf->_name);
    };
    #endif
    
    #ifdef X
    // This executes the code or print a message, but if the object is deallocated when
    // the execution starts (#1), it will lead to errors (in this case it prints nil).
    __block __weak Person *weakSelf = self;
    self.salute = ^{ 
        if (weakSelf){ 
            NSLog(@"%@", [weakSelf name]); /*1*/
        } else {
            NSLog(@"object deallocated");
        }
    };
    #endif
    
    #ifdef YES
    // This executes the code or print a message. If the object is deallocated when
    // the execution starts (#1), the strong reference keeps the code running correctly.
    __block __weak Person *weakSelf = self;
    self.salute = ^{
        __strong Person *strongSelf = weakSelf;
        if (strongSelf){
            NSLog(@"%@", strongSelf->_name); /*1*/
        } else {
            NSLog(@"can't execute, object is gone");
        }
    };
    #endif

    return self;
}


-(void) execute:(salute_t)salute delay:(long long)seconds 
{
    long long delaySeconds = 1;
    long long delayNanoseconds = ((long long) delaySeconds)*NSEC_PER_SEC;
    dispatch_time_t delay = dispatch_time(DISPATCH_TIME_NOW, delayNanoseconds);
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0UL);
    dispatch_after(delay, queue, ^{
        salute();
    });
    NSLog(@"scheduled");
}


@end