Merge branch 'release-candidate' into stable

CHANGELOG.md

@@ -1,3 +1,22 @@
+# 3.3.0
+
+This minor release deprecates some behavior and replaces it with a new API.
+
+## New deprecations
+
+- `MDMTransitionWithFallback` nil behavior is now deprecated. In order to fall back to system
+transitions you must now conform to `MDMTransitionWithFeasibility` and return NO.
+
+## Source changes
+
+* [Backport MDMTransitionWithFeasibility from the v4.0.0 release for v3.1 clients.](https://github.com/material-motion/transitioning-objc/commit/1f994d03c7971001cc8faafe61b3ed2f55bca118) (Jeff Verkoeyen)
+
+## API changes
+
+### MDMTransitionWithFeasibility
+
+*new* protocol `MDMTransitionWithFeasibility`.
+
 # 3.2.1
 
 This patch release resolves Xcode 9 compiler warnings.

MotionTransitioning.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
   s.name         = "MotionTransitioning"
   s.summary      = "Light-weight API for building UIViewController transitions."
-  s.version      = "3.2.1"
+  s.version      = "3.3.0"
   s.authors      = "The Material Motion Authors"
   s.license      = "Apache 2.0"
   s.homepage     = "https://github.com/material-motion/transitioning-objc"

Podfile.lock

@@ -1,6 +1,6 @@
 PODS:
   - CatalogByConvention (2.1.1)
-  - MotionTransitioning (3.2.1)
+  - MotionTransitioning (3.3.0)
 
 DEPENDENCIES:
   - CatalogByConvention
@@ -12,7 +12,7 @@ EXTERNAL SOURCES:
 
 SPEC CHECKSUMS:
   CatalogByConvention: c3a5319de04250a7cd4649127fcfca5fe3322a43
-  MotionTransitioning: 01e7fcd6e2974985057109e0a4c98ea546cd5947
+  MotionTransitioning: caaa488e0469d93f004793b96a2ed04447af808d
 
 PODFILE CHECKSUM: db2e7ac8d9d65704a2cbffa0b77e39a574cb7248
 

src/MDMTransition.h

@@ -72,6 +72,26 @@ NS_SWIFT_NAME(TransitionWithFallback)
 
 @end
 
+/**
+ A transition with feasibility can indicate whether it's capable of handling a given context.
+ */
+NS_SWIFT_NAME(TransitionWithFeasibility)
+@protocol MDMTransitionWithFeasibility <MDMTransition>
+
+/**
+ Asks the receiver whether it's capable of performing the transition with the given context.
+
+ If NO is returned, the receiver's startWithContext: will not be invoked.
+ If the transition is infeasible, then a default UIKit transition will be performed instead.
+
+ If YES is returned, the receiver's startWithContext: will be invoked.
+
+ The context's containerView will be nil during this call.
+ */
+- (BOOL)canPerformTransitionWithContext:(nonnull id<MDMTransitionContext>)context;
+
+@end
+
 /**
  A transition with presentation is able to customize the overall presentation of the transition,
  including adding temporary views and changing the destination frame of the presented view

src/private/MDMViewControllerTransitionContext.m

@@ -46,7 +46,15 @@ - (nonnull instancetype)initWithTransition:(nonnull id<MDMTransition>)transition
 
     _completionBlocks = [NSMutableArray array];
 
-    _transition = [self fallbackForTransition:_transition];
+    if ([_transition respondsToSelector:@selector(canPerformTransitionWithContext:)]) {
+      id<MDMTransitionWithFeasibility> withFeasibility = (id<MDMTransitionWithFeasibility>)_transition;
+      if (![withFeasibility canPerformTransitionWithContext:self]) {
+        _transition = nil;
+      }
+    } else {
+      _transition = [self fallbackForTransition:_transition];
+    }
+
     if (!_transition) {
       return nil;
     }