add view.mas_attribute(...)

@@ -30,6 +30,7 @@
 @property (nonatomic, strong, readonly) MASViewAttribute *mas_centerX;
 @property (nonatomic, strong, readonly) MASViewAttribute *mas_centerY;
 @property (nonatomic, strong, readonly) MASViewAttribute *mas_baseline;
+@property (nonatomic, strong, readonly) MASViewAttribute *(^mas_attribute)(NSLayoutAttribute attr);
 
 /**
  *	a key to associate with this view

@@ -72,6 +72,13 @@
     return [[MASViewAttribute alloc] initWithView:self layoutAttribute:NSLayoutAttributeBaseline];
 }
 
+- (MASViewAttribute *(^)(NSLayoutAttribute))mas_attribute
+{
+    return ^(NSLayoutAttribute attr) {
+        return [[MASViewAttribute alloc] initWithView:self layoutAttribute:attr];
+    };
+}
+
 #pragma mark - associated properties
 
 - (id)mas_key {

@@ -27,6 +27,7 @@
 @property (nonatomic, strong, readonly) MASViewAttribute *centerX;
 @property (nonatomic, strong, readonly) MASViewAttribute *centerY;
 @property (nonatomic, strong, readonly) MASViewAttribute *baseline;
+@property (nonatomic, strong, readonly) MASViewAttribute *(^attribute)(NSLayoutAttribute attr);
 
 - (NSArray *)makeConstraints:(void(^)(MASConstraintMaker *make))block;
 - (NSArray *)updateConstraints:(void(^)(MASConstraintMaker *make))block;
@@ -51,6 +52,7 @@ MAS_ATTR_FORWARD(height);
 MAS_ATTR_FORWARD(centerX);
 MAS_ATTR_FORWARD(centerY);
 MAS_ATTR_FORWARD(baseline);
+MAS_ATTR_FORWARD(attribute);
 
 - (NSArray *)makeConstraints:(void(^)(MASConstraintMaker *))block {
     return [self mas_makeConstraints:block];