Where is UIView.init() documented?

Question

In the folowing example:

import UIKit

class MyView: UIView
{
    override init(frame: CGRect) {
       super.init(frame: frame)
       print ("...init with frame")
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        print("...init with coder")
    }
}

.......

 let var = MyView() //  "...init with frame" gets printed

So it seems MyView() calls UIView.init() which in turn calls init(frame: CGRect). However according to the UIView documentation there is only a init(frame:) (and (init:coder)).

According to the documenation for NSObject. init()

does no initialization; it simply returns self.

So there must be a UIView.init() that overrides NSObject.init() and in turn calls init(frame:). But this UIView.init() isn't documented? Or am I missing this documentation?

Answer 1

I have found no documentation for UIView.init, but UIView.init does exist. If you set a breakpoint at your print ("...init with frame"), you will see the call to [UIView init] in the Debug Navigator. The assembly code clearly shows it calling objc_msgSend to initWithFrame: using CGRectZero as the frame:

UIKit`-[UIView init]:
    0x10b3ba160 <+0>:  pushq  %rbp
    0x10b3ba161 <+1>:  movq   %rsp, %rbp
    0x10b3ba164 <+4>:  subq   $0x20, %rsp
    0x10b3ba168 <+8>:  movq   0xc52f71(%rip), %rsi      ; "initWithFrame:"
    0x10b3ba16f <+15>: movq   0xcd5f72(%rip), %rax      ; (void *)0x000000010f732690: CGRectZero
    0x10b3ba176 <+22>: movq   0x18(%rax), %rcx
    0x10b3ba17a <+26>: movq   %rcx, 0x18(%rsp)
    0x10b3ba17f <+31>: movq   0x10(%rax), %rcx
    0x10b3ba183 <+35>: movq   %rcx, 0x10(%rsp)
    0x10b3ba188 <+40>: movq   (%rax), %rcx
    0x10b3ba18b <+43>: movq   0x8(%rax), %rax
    0x10b3ba18f <+47>: movq   %rax, 0x8(%rsp)
    0x10b3ba194 <+52>: movq   %rcx, (%rsp)
    0x10b3ba198 <+56>: callq  *0xcd7042(%rip)           ; (void *)0x000000010c8b9800: objc_msgSend
    0x10b3ba19e <+62>: addq   $0x20, %rsp
    0x10b3ba1a2 <+66>: popq   %rbp
    0x10b3ba1a3 <+67>: retq