Synopsis
iOS Curve Interpolation consists of two main components:
- A category on UIBezierCurvePath, UIBezierCurvePath+Interpolation.
- A small iOS app that demonstrates the categories use.
Example
#include "UIBezierCurvePath+Interpolation.h"
const char *encoding = @encode(CGPoint);
NSMutableArray *array = [NSMutableArray new];
// Add 4 CGPoints as NSValue
[array addObject:[NSValue valueWithBytes:&CGPointMake(0.0, 0.0) objCType:encoding];
[array addObject:[NSValue valueWithBytes:&CGPointMake(0.0, 1.0) objCType:encoding];
[array addObject:[NSValue valueWithBytes:&CGPointMake(1.0, 1.0) objCType:encoding];
[array addObject:[NSValue valueWithBytes:&CGPointMake(1.0, 0.0) objCType:encoding];
UIBezierPath *path = [interpolateCGPointsWithCatmullRom:array closed:NO alpha:0.5];
// Use the pathMotivation
To add an easy-to-use category for curve interpolation onto UIBezierPath. Also to provide a small iOS app for demonstrating/testing the interpolation inputs (Hermite vs. Catmull-Rom, alpha value effects, and open/closed option).
Installation
Clone the repo, open the Xcode project in Xcode 5+.
The UIBezierPath+Interpolation.h/.m is standalone, provided you also include CGPointExtension.h/.m (which are also included in the Xcode project).
API Reference
// pointsAsNSValues must be NSValue objects containing CGPoints.
//
// ex:
// const char *encoding = @encode(CGPoint);
// NSValue *pointAsValue = [NSValue valueWithBytes:&cgPoint objCType:encoding];
// 0.0 <= alpha <= 1.0
+(UIBezierPath *)interpolateCGPointsWithCatmullRom:(NSArray *)pointsAsNSValues closed:(BOOL)closed alpha:(float)alpha;
+(UIBezierPath *)interpolateCGPointsWithHermite:(NSArray *)pointsAsNSValues closed:(BOOL)closed;