iOS 7 spring damping and stiffness calculation

ios7springs.m

@interface NSObject ()
- (void)generateSpringPropertiesForDuration:(float)arg1 damping:(float)arg2 velocity:(float)arg3;
- (id)_defaultAnimationForKey:(id)arg1;
@end

// This object calculates the damping and stiffness coefficients, given a damping value (0...1], a velocity, and a duration.
id obj = [[NSClassFromString(@"UIViewSpringAnimationState") alloc] init];

[obj generateSpringPropertiesForDuration:10 damping:0.5 velocity:10];

// Prints the calculated damping and stiffness coefficients.
NSLog(@"%@", [[obj _defaultAnimationForKey:@"test"] debugDescription]);