What is the difference between ccScaleBy and ccScaleTo in cocos2d?

I am scaling my sprite object in cocos2d using the CCScaleTo method. It is not perfect scaling so I use this code:

id action1=[CCScaleTo actionWithDuration:0.5 scale:1.25];
id action2=[CCScaleBy actionWithDuration:0.5 scale:.25];
id action3=[CCScaleTo actionWithDuration:0.5 scale:1.25];
id action4=[CCScaleTo actionWithDuration:0.5 scale:.25];

[timeUpImg runAction:[CCSequence actions:action1,action2,action3,action4,nil]];

This is working perfectly.

I don't know the difference between cc开发者_JAVA百科ScaleBy and CCScaleTo and also how to use the "reverse" method. Can someone explain it please?

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CCScaleTo scales the node/sprite to an absolute scale factor while CCScaleBy scales it by a factor relative to current scale.

For example, suppose a node currently has scale 0.25:

• [CCScaleTo actionWithDuration:0.5 scale:2.0] will modify the scale to 2.0 (simply ignores the current scale)

• [CCScaleBy actionWithDuration:0.5 scale:2.0] will modify the scale to 0.5 (0.25 * 2.0)

On the second question, the reverse method returns an instance of CCAction subclass that gives the reverse effect of the original action. For example: [[CCScaleBy actionWithDuration:0.5 scale:2.0] reverse] will return [CCScaleBy actionWithDuration:0.5 scale:0.5], and [[CCScaleBy actionWithDuration:0.5 scale:4.0] reverse] will return [CCScaleBy actionWithDuration:0.5 scale:0.25]