my iphone apps

ctrl-drag objects into your view to code in your controller(outlets and actions)

option click to get help in your code.

@interface  .h

@implementation .m

add a private @interface to .m

pointers to an object, type id or a static type(eg UIButton *)

invoke a method, using square bracket [] notation

dot notation for property

lazilly instantiate an object by implementing your own @property getter

wrap a primitive type (double) in an object (using NSNumber)

constant NSString @""

 

当你拖拽ui component 进入controller.h时， 系统会生成一个public property IBOutlet.(connection 类型为Outlet)

@property (weak, nonatomic) IBOutlet UILabel *display;

剩下的 你需要在controller.m 文件中

@synthesize 分配一下storage

@synthesize display = _display;

当你拖拽一个ui component 进入controller.m时，系统知道你要生成相应ui的action(connection 类型为Action)

- (IBActoin) digitPressed: (UIButton * id) sender
{
    NSString * digit = [sender currentTitle];
    self.display.text =  [self.display.text stringByAppendingString:digit];
} 

 

NSLog:

%@ 表示一个对象，就像%d 表示数字,%g 表示float 一样

to declare private property in controller.m file

@interface  CalculatorViewController()

@property (nonatomic) BOOL isInTheMiddle;

@end