Button的imageEdgeInsets和titleEdge

button中自带的title和image，给button设置这两个属性，默认是居中，UIEdgeInsetsMake(0, 0, 0, 0), imageEdgeInsets和titleEdgeInsets属性可以改变偏移量

button.imageEdgeInsets= UIEdgeInsetsMake(0, -40, 0, 0);
button.titleEdgeInsets = UIEdgeInsetsMake(0, -40, 0, 0);

向左偏移40