[YogaKit] support auto apply layout.

- support auto apply layout
- build Yoga & YogaKit framework as staticlib;
- update YogaKitSample.

YogaKit/Source/UIView+Yoga.m

@@ -35,3 +35,88 @@ static const void* kYGYogaAssociatedKey = &kYGYogaAssociatedKey;
 }
 
 @end
+
+
+static const void* kYGBoundsSizeAssociatedKey = &kYGBoundsSizeAssociatedKey;
+static void YogaSwizzleInstanceMethod(Class cls, SEL originalSelector, SEL swizzledSelector);
+
+@implementation UIView (YogaKitAutoApplyLayout)
+
++ (void)load {
+    static dispatch_once_t onceToken = 0;
+    dispatch_once(&onceToken, ^{
+        YogaSwizzleInstanceMethod(self, @selector(initWithFrame:), @selector(_yoga_initWithFrame:));
+        YogaSwizzleInstanceMethod(self, @selector(setFrame:), @selector(_yoga_setFrame:));
+        YogaSwizzleInstanceMethod(self, @selector(setBounds:), @selector(_yoga_setBounds:));
+    });
+}
+
+- (CGSize)_yoga_boundsSize {
+    NSValue *value = (NSValue *)objc_getAssociatedObject(self, kYGBoundsSizeAssociatedKey);
+
+    return value ? value.CGSizeValue : CGSizeMake(YGUndefined, YGUndefined);
+}
+
+- (void)set_yoga_boundsSize:(CGSize)size {
+    objc_setAssociatedObject(self,
+                             kYGBoundsSizeAssociatedKey,
+                             [NSValue valueWithCGSize:size],
+                             OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}
+
+- (instancetype)_yoga_initWithFrame:(CGRect)frame {
+    id _self = [self _yoga_initWithFrame:frame];
+    if (_self) {
+        [self _yoga_applyLayout];
+    }
+
+    return _self;
+}
+
+- (void)_yoga_setFrame:(CGRect)frame {
+    [self _yoga_setFrame:frame];
+
+    [self _yoga_applyLayout];
+}
+
+- (void)_yoga_setBounds:(CGRect)bounds {
+    [self _yoga_setBounds:bounds];
+
+    [self _yoga_applyLayout];
+}
+
+- (void)_yoga_applyLayout {
+    if (self.isYogaEnabled && self.yoga.isEnabled) {
+        CGSize size = self.bounds.size;
+        CGSize prev = self._yoga_boundsSize;
+        if (!CGSizeEqualToSize(size, prev)) {
+            self._yoga_boundsSize = size;
+            [self.yoga applyLayoutPreservingOrigin:YES];
+        }
+    }
+}
+
+@end
+
+
+static void YogaSwizzleInstanceMethod(Class cls, SEL originalSelector, SEL swizzledSelector) {
+    if (!cls || !originalSelector || !swizzledSelector) {
+        return;
+    }
+
+    Method originalMethod = class_getInstanceMethod(cls, originalSelector);
+    Method swizzledMethod = class_getInstanceMethod(cls, swizzledSelector);
+    if (!originalMethod || !swizzledMethod) {
+        return;
+    }
+
+    IMP swizzledIMP = method_getImplementation(swizzledMethod);
+    if (class_addMethod(cls, originalSelector, swizzledIMP, method_getTypeEncoding(swizzledMethod))) {
+        class_replaceMethod(cls,
+                            swizzledSelector,
+                            method_getImplementation(originalMethod),
+                            method_getTypeEncoding(originalMethod));
+    } else {
+        method_exchangeImplementations(originalMethod, swizzledMethod);
+    }
+}