解决方法
如果你喜欢,可以使用CGRectInset:
double pct = 0.2; CGRect newRect = CGRectInset(oldRect,-CGRectGetWidth(oldRect)*pct/2,-CGRectGetHeight(oldRect)*pct/2);
要减小大小,请删除-s.
旁注:比{10,100,100}大20%的CGRect为{0,120}.
编辑:如果意图是按面积增加,那么这样做(即使是不是方形的矩形):
CGFloat width = CGRectGetWidth(oldRect); CGFloat height = CGRectGetHeight(oldRect); double pct = 1.2; // 20% increase double newWidth = sqrt(width * width * pct); double newHeight = sqrt(height * height * pct); CGRect newRect = CGRectInset(oldRect,(width-newWidth)/2,(height-newHeight)/2);