UILabel的常见设置
@property(nonatomic,copy) NSString *text; 显示的文字
@property(nonatomic,retain) UIFont *font; 字体
@property(nonatomic,retain) UIColor *textColor; 文字颜色
@property(nonatomic) NSTextAlignment textAlignment; 对齐模式（比如左对齐、居中对齐、右对齐）
UIFont的常见设置
+ (UIFont *)systemFontOfSize:(CGFloat)fontSize; 系统默认字体
+ (UIFont *)boldSystemFontOfSize:(CGFloat)fontSize; 粗体
+ (UIFont *)italicSystemFontOfSize:(CGFloat)fontSize; 斜体
UIButton的常见设置
- (void)setTitle:(NSString *)title forState:(UIControlState)state; 设置按钮的文字
- (void)setTitleColor:(UIColor *)color forState:(UIControlState)state; 设置按钮的文字颜色
- (void)setImage:(UIImage *)image forState:(UIControlState)state; 设置按钮内部的小图片
- (void)setBackgroundImage:(UIImage *)image forState:(UIControlState)state; 设置按钮的背景图片
btn.titleLabel.font = [UIFont systemFontOfSize:13]; 设置按钮的文字字体（需要拿到按钮内部的label来设置）
- (NSString *)titleForState:(UIControlState)state; 获得按钮的文字
- (UIColor *)titleColorForState:(UIControlState)state; 获得按钮的文字颜色
- (UIImage *)imageForState:(UIControlState)state; 获得按钮内部的小图片
- (UIImage *)backgroundImageForState:(UIControlState)state; 获得按钮的背景图片