po
po是print-object的简写，可用来打印所有NSObject对象。使用举例如下：
(gdb) po self
<LauncherViewController: 0x552c570>
(gdb) po [self view]
<UIView: 0x544eb80; frame = (0 0; 320 411); autoresize = W+H; layer = <CALayer: 0x544ebb0>>
(gdb) print-object [self view]
<UIView: 0x544eb80; frame = (0 0; 320 411); autoresize = W+H; layer = <CALayer: 0x544ebb0>>
p
p是print的简写，可以用来打印所有的简单类型，如int, float，结构体等。使用举例如下：
(gdb) p self
$1 = (LauncherViewController *) 0x552c570
(gdb) p [[self view] size]
Unable to call function “objc_msgSend” at 0x1e7e08c: no return type information available.
To call this function anyway, you can cast the return type explicitly (e.g. ‘print (float) fabs (3.0)’)
(gdb) p (CGSize)[[self view] size]
$1 = {
width = 320,
height = 411
}
(gdb) print (CGSize)[[self view] size]
$2 = {
width = 320,
height = 411
}
call
call即是调用的意思。其实上述的po和p也有调用的功能。因此一般只在不需要显示输出，或是方法无返回值时使用call。使用举例如下：
(gdb) call [[self view]sizeToFit]
Unable to call function “objc_msgSend” at 0x1e7e08c: no return type information available.
To call this function anyway, you can cast the return type explicitly (e.g. ‘print (float) fabs (3.0)’)
(gdb) call (void)[[self view]sizeToFit]
(gdb) call [[self view] size]
Unable to call function “objc_msgSend” at 0x1e7e08c: no return type information available.
To call this function anyway, you can cast the return type explicitly (e.g. ‘print (float) fabs (3.0)’)
(gdb) call (void)[[self view] size]