The touch moves from left to right. This direction is the default.

var direction: UISwipeGestureRecognizer.Direction. The permitted direction of the swipe for this gesture recognizer. var numberOfTouchesRequired: Int. The number of touches necessary for swipe recognition.

Discussion. The default value of this property is right. You may specify more than one direction to track swipes in multiple directions with the same gesture recognizer.

Jul 22, 2010 · Seems like there is a bug. You can specify the allowed direction(s) as you did. But when you try to access the actual direction that triggered the swipe in the action selector method you still get the bit mask you originally set (for the allowed directions).. This means that checks for the actual direction will always fail when more than 1 direction is allowed.

Objective-C is a thin layer atop C and is a "strict superset" of C, meaning that it is possible to compile any C program with an Objective-C compiler and to freely include C language code within an Objective-C class. Objective-C derives its object syntax from Smalltalk. All of the syntax for non-object-oriented operations (including primitive variables, pre-processing, expressions, …

Sep 17, 2014 · Objective-C uses protocols to define a group of related methods, such as the methods an object might call on its delegate, which are either optional or required. Any class can indicate that it adopts a protocol, which means that it must also provide implementations for all of the required methods in the protocol.

Dec 03, 2015 · With Swift, object types can be divided into two general categories, according to whether they observe reference or value conventions. An object of the class type is treated as a reference in assignments and when passed as a parameter, just like the @class behaves in Objective-C. Fundamental types, such as integers and floating point values ...

Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. This is the main programming language used by Apple for the OS X and iOS operating systems and their respective APIs, Cocoa and Cocoa Touch. This reference will take you through simple and practical approach while learning Objective-C …

Objective-C enables this style with automatic conversions and carefully designed overflow behaviors, but these exact features can cause serious security bugs, so Swift doesn't include them. Instead, Swift requires you to explicitly convert unsigned types to signed if you wanted signed arithmetic, and stops execution if unsigned arithmetic would produce a negative result.

Oct 04, 2017 · Paul Hudson October 4th 2017 @twostraws. For several years after the iOS SDK was announced, developers were flocking to Objective-C as they sought to get their slice of the app development gold rush. But those times are gone: Swift has been with us for over three years now, and has largely pushed its older sibling from the limelight.