CAGradientLayer - 漸變顏色(iOS)

CAGradientLayer繼承自CALayer, 是 Core Animation 中的一個, 主要功能是用來時間漸變顏色圖層.

效果以下所示:

代碼實現:

// 添加漸變色層
    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.frame = self.bounds;

    gradientLayer.colors = [NSArray arrayWithObjects:
                            (id)[kColorFromRGB(0xF6C48E) CGColor],
                            (id)[kColorFromRGB(0xBB7FCB) CGColor],
                            (id)[kColorFromRGB(0x6DD2E5) CGColor], nil];
    gradientLayer.startPoint = CGPointMake(0, 0.4);
    gradientLayer.endPoint = CGPointMake(1, 0.6);
    _gradientLayer = gradientLayer;

    [self.layer insertSublayer:gradientLayer atIndex:0];

這樣的功能, 實現起來仍是比較簡單的, 蘋果給咱們所有都封裝好了, 只須要調用幾個簡單的方法便可.

事實上, CAGradientLayer類也是比較簡單的, 只提供以下幾個方法和屬性, 好吧, 當了解以後, 以爲太簡單了, 沒什麼好說的了 ....

@interface CAGradientLayer : CALayer

/* The array of CGColorRef objects defining the color of each gradient
 * stop. Defaults to nil. Animatable. */

@property(nullable, copy) NSArray *colors;

/* An optional array of NSNumber objects defining the location of each
 * gradient stop as a value in the range [0,1]. The values must be
 * monotonically increasing. If a nil array is given, the stops are
 * assumed to spread uniformly across the [0,1] range. When rendered,
 * the colors are mapped to the output colorspace before being
 * interpolated. Defaults to nil. Animatable. */

@property(nullable, copy) NSArray<NSNumber *> *locations;

/* The start and end points of the gradient when drawn into the layer's
 * coordinate space. The start point corresponds to the first gradient
 * stop, the end point to the last gradient stop. Both points are
 * defined in a unit coordinate space that is then mapped to the
 * layer's bounds rectangle when drawn. (I.e. [0,0] is the bottom-left
 * corner of the layer, [1,1] is the top-right corner.) The default values
 * are [.5,0] and [.5,1] respectively. Both are animatable. */

@property CGPoint startPoint;
@property CGPoint endPoint;

/* The kind of gradient that will be drawn. Currently the only allowed
 * value is `axial' (the default value). */

@property(copy) NSString *type;

@end