点语法调用的是属性，实质上是调用的getter方法。如：
@interface MyTestObject : NSObject
{
@public //不加该句的话，外部无法调用
NSString *name;
}
@property (nonatomic) NSString *school;
@end
MyTestObject *obj = [[MyTestObject alloc] init];
obj->name = @"小明";
obj.school = @"重点高中";
