self.titleBtn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
self.titleBtn.contentEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);
self.titleBtn.titleEdgeInsets = UIEdgeInsetsMake(0, 15, 0, 0);
self.titleBtn.imageEdgeInsets = UIEdgeInsetsZero;
调整按钮的子控件titleLable和imageView的间距的属性和用法
原文：http://www.cnblogs.com/fs-ios/p/4973335.html