instancetype)initWithItems:(NSArray *)itemsParametersitemsThe dynamic items that you want to be subject to the gravity behavior.Return ValueThe initialized gravity behavior, or nil if there was a problem initializing the object.
Discussion
AvailabilityAvailable in iOS 7.0 and later.Declared InremoveItem:Removes a specific dynamic item from the gravity behavior.- (void)removeItem:(id&UIDynamicItem&)itemParametersitemThe dynamic item that you want to remove.Discussion
AvailabilityAvailable in iOS 7.0 and later.Declared InsetAngle:magnitude:Sets the angle and magnitude of the gravity vector for the behavior.- (void)setAngle:(CGFloat)angle magnitude:(CGFloat)magnitudeParametersangleThe radian angle for the gravity vector, using standard UIKit geometry.magnitudeThe acceleration for the gravity, with a value of 1.0 corresponding to 1000 points / second??.AvailabilityAvailable in iOS 7.0 and later.See Also
  @property angle
  @property magnitudeDeclared In
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Definition:
A shape, formed by two lines or rays diverging from a common point (the vertex).
Adjust the angle below by dragging the orange dot.
Attributes
is the common point at which the two lines or rays are joined.
Point B is the figure above is the vertex of the angle
∠ABC.
The legs (sides)
of an angle are the two lines that make it up.
In the figure above, the line segments
are the legs of the angle
∠ABC.
The interior of an angle is the space in the 'jaws' of the angle extending out to infinity.
All the space on the plane that is not the interior.
Identifying an angle
An angle can be identified in two ways.
Like this: ∠ABC
The angle symbol, followed by three points that define the angle, with the middle letter being the vertex, and the other two on the legs.
So in the figure above the angle would be ∠ABC or ∠CBA.
So long as the vertex is the middle letter, the order is not important.
As a shorthand
we can use the 'angle' symbol.
For example '∠ABC' would be read as 'the angle ABC'.
Or like this: ∠B
Just by the vertex, so long as it is not ambiguous.
So in the figure above the angle could also be called simply&
'∠B'
Measure of an angle
The size of an angle is measured in degrees (see ).
When we say 'the angle ABC' we mean the actual angle object.
If we want to talk about the size, or measure, of the angle in degrees, we should say 'the measure of the angle ABC' - often written m∠ABC.
However, many times we will see '∠ABC=34&'.
Strictly speaking this is an error.
It should say 'm∠ABC=34&'
Types of angle
Altogether, there are six types of angle as listed below.
Click on an image for a full description of that type and a corresponding interactive applet.
Less than 90&
Exactly 90&
Between 90& and 180&
Exactly 180&
Between 180& and 360&
Exactly 360&
In Trigonometry
When used in ,
angles have some extra properties:
They can have a measure greater than 360&, can be positive and negative, and are positioned on a coordinate grid with x and y axes.
They are usually measured in
instead of
For more on this see .
Angle construction
In the Constructions chapter, there are animated demonstrations of various
of angles using only a compass and straightedge.
Constructing a 90& angle (perpendicular, right angle) at:
Other angle topics
Angle Types
Angle relationships
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