KAAOptional is Objective-C library which adds Optional support.

• Features
• Usage
• Installation

Features

• Lightweight Generics for content value
• Dictionary now can return Optionals on subscript methods call
• Full Java 8 syntax (streams, control flow, functional extensions: map, flatMap, filter)
• Optional behave same way as swift optional: chaining support, doesn't crash on unrecognised message sent if empty and crashes if not and value cannot respond, proxies messages to it's value, behaves same on equality.
• Dot notation support
• Tested and well documented

Usage

Control flow:

Now in swift 5.0:

func fetch() -> String? {
  //Some big work
  ...
  return "123"
}

if let e = fetch() {
  print(e)
} else {
  //Do something
  print("Empty")
}

In Objective-C with KAAOptional:

- (nonnull Optional<NSString *> *)fetch {
    //Some big work
    ...
    return Optional.of(@"123");
}

[[self fetch] ifPresent:^(NSNumber * _Nonnull aValue) {
      NSLog(@"%@", aValue);
    } orElse:^{
        NSLog(@"Empty");
}]];

Get functional extensions.

Now in swift 5.0:

var res = "404"

if let e = fetch(),
let r = Int(e),
r > 123 {
    res = e
}
print(res)

In Objective-C with KAAOptional using functional extensions:

- (nonnull Optional<NSString *> *)fetch {
    //Some big work
    ...
    return Optional.of(@"123");
}

__auto_type const a = [[[self fetch] filter:^BOOL(NSString * _Nonnull aValue) {
      return aValue.integerValue > 123 && [aValue isKindOfClass:[NSString class]];
  }] orElse:@"404"];

NSLog(@"%@", a);

or with .dot notation

__auto_type const b = [self fetch]
  .filter(^BOOL(NSString * _Nonnull aValue) {
      return aValue.integerValue > 123 && [aValue isKindOfClass:[NSString class]];
  }).orElse(@"404");
NSLog(@"%@", b);

Supports Java 8 style

• stream
• map
• flatMap
• filter

Subscript on Dictionary now returns Optional.

In swift:

var a = ["K": "V"]["K"] // Returns Optional
if let a = a { // Unwraps

}

In Objective-C using Optional

You can enable it pointwise by calling "op" method on Dictionary. Or enable it by default by calling "[NSDictionary kaa_enableOptionalByDefault]" once anywhere. ⚠️⚠️⚠️ WARNING ⚠️⚠️⚠️ Beware - even though Optional behaves like proxy: -isEqual, -isKindOfClass, -isMemberOfClass will work fine on old code, calling +class and +superClass - will return Optional and NSObject.

__auto_type a = @{
                  @"K": @"V"
                 }.op;
NSLog(@"%@", a[@"K"]); //-> <Optional: 0xSomeAddress, Value: @"V">
NSLog(@"%@", a[@"wrongKey"]); //-> <Optional: 0xSomeAddress, Value: nil>

Note: Following construct will not crash due to internal catch logic. So your old code is safe!

[NSDictionary kaa_enableOptionalByDefault];
...
__auto_type a = [@{
                  @"K": [MyObject new]
                 }[@"K2"] myOldMessage];
// Will react same as nil messaging
NSLog(@"I didn't crash!");

Note: Following construct will proxy to value. So it's also safe!

[NSDictionary kaa_enableOptionalByDefault];
...
NSUInteger i = [@{@"K": @"V"} length];
NSLog(@"%@", @(i)); // Will output = 1

You can even chain subscript!!!

__auto_type a = @{
                     @"K": @[@{@"K2": @"V"}]
                     };
   //By using subscript, you get optional! An it can be chained!
   __unused NSString *b = a[@"K"][0][@"K2"].orElse(@"V2");

And of course - just chain optionals!!!

NSString *a = Optional.of(Optional.of(@"123")).get;

Equality

In swift

var a = ["K": "V"]["K"]
print(a == "V") // true

In Objective-C using KAAOptional

[@{@"K": @"V"}.op[@"K"] isEqual:@"K"] // YES

Installation

CocoaPods

target '<Your Target Name>' do
    pod 'KAAOptional', '~> 1.0.2'
end

Carthage

github "neisip/KAAOptional"

License

KAAOptional is released under the MIT license. See LICENSE for details.