NSString *string = @”hello bla bla”; if ([string rangeOfString:@”bla”].location == NSNotFound) { NSLog(@”string does not contain bla”); } else { NSLog(@”string contains bla!”); } The key is noticing that rangeOfString: returns an NSRange struct, and the documentation says that it returns the struct {NSNotFound, 0} if the “haystack” does not contain the “needle”. And if … Read more
You may have a bad connection in your xib. I’ve had this error many times. While TechZen’s answer is absolutely right in this case, another common cause is when you change the name of a IBOutlet property in your .h/.m which you’ve already connected up to File’s Owner in the nib. From your nib: Select … Read more
Solution The compiler is warning about this for a reason. It’s very rare that this warning should simply be ignored, and it’s easy to work around. Here’s how: if (!_controller) { return; } SEL selector = NSSelectorFromString(@”someMethod”); IMP imp = [_controller methodForSelector:selector]; void (*func)(id, SEL) = (void *)imp; func(_controller, selector); Or more tersely (though hard … Read more
Compare method Either you implement a compare-method for your object: – (NSComparisonResult)compare:(Person *)otherObject { return [self.birthDate compare:otherObject.birthDate]; } NSArray *sortedArray = [drinkDetails sortedArrayUsingSelector:@selector(compare:)]; NSSortDescriptor (better) or usually even better: NSSortDescriptor *sortDescriptor; sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@”birthDate” ascending:YES]; NSArray *sortedArray = [drinkDetails sortedArrayUsingDescriptors:@[sortDescriptor]]; You can easily sort by multiple keys by adding more than one to … Read more
Important: This check should always be performed asynchronously. The majority of answers below are synchronous so be careful otherwise you’ll freeze up your app. Swift Install via CocoaPods or Carthage: https://github.com/ashleymills/Reachability.swift Test reachability via closures let reachability = Reachability()! reachability.whenReachable = { reachability in if reachability.connection == .wifi { print(“Reachable via WiFi”) } else { … Read more
This question seems to be very popular here on Stack Overflow so I thought I would try and give a better answer to help out people starting in the world of iOS like me. Passing Data Forward Passing data forward to a view controller from another view controller. You would use this method if you wanted … Read more
Use NSAppTransportSecurity: You have to set the NSAllowsArbitraryLoads key to YES under NSAppTransportSecurity dictionary in your info.plist file.
TL;DR: Don’t like reading? Jump straight to the sample projects on GitHub: iOS 8 Sample Project – Requires iOS 8 iOS 7 Sample Project – Works on iOS 7+ Conceptual Description The first 2 steps below are applicable regardless of which iOS versions you are developing for. 1. Set Up & Add Constraints In your … Read more
You will only need a ScrollView if the contents you have now do not fit in the iPhone screen. (If you are adding the ScrollView as the superview of the components just to make the TextField scroll up when keyboard comes up, then it’s not needed.) The standard way to prevent the TextFields from being … Read more
The last two are identical; “atomic” is the default behavior (note that it is not actually a keyword; it is specified only by the absence of nonatomic — atomic was added as a keyword in recent versions of llvm/clang). Assuming that you are @synthesizing the method implementations, atomic vs. non-atomic changes the generated code. If … Read more