iOS代码瘦身实践之如何删除无用的类

#binary_file_arch: distinguish Big-Endian and Little-Endian
#file -b output example: Mach-O 64-bit executable arm64
binary_file_arch = os.popen('file -b ' + path).read().split(' ')[-1].strip()

def pointers_from_binary(line, binary_file_arch):
 line = line[16:].strip().split(' ')
 pointers = set()
 if binary_file_arch == 'x86_64':
  #untreated line example:00000001030cec80	d8 75 15 03 01 00 00 00 68 77 15 03 01 00 00 00
  pointers.add(''.join(line[4:8][::-1] + line[0:4][::-1]))
  pointers.add(''.join(line[12:16][::-1] + line[8:12][::-1]))
  return pointers
 #arm64 confirmed,armv7 arm7s unconfirmed
 if binary_file_arch.startswith('arm'):
  #untreated line example:00000001030bcd20	03138580 00000001 03138878 00000001
  pointers.add(line[1] + line[0])
  pointers.add(line[3] + line[2])
  return pointers
 return None

def class_ref_pointers(path, binary_file_arch):
  ref_pointers = set()
  lines = os.popen('/usr/bin/otool -v -s __DATA __objc_classrefs %s' % path).readlines()
  for line in lines:
    pointers = pointers_from_binary(line, binary_file_arch)
    ref_pointers = ref_pointers.uNIOn(pointers)
  return ref_pointers

def class_list_pointers(path, binary_file_arch):
  list_pointers = set()
  lines = os.popen('/usr/bin/otool -v -s __DATA __objc_classlist %s' % path).readlines()
  for line in lines:
    pointers = pointers_from_binary(line, binary_file_arch)
    list_pointers = list_pointers.union(pointers)
  return list_pointers

unref_pointers = class_list_pointers(path, binary_file_arch) - class_ref_pointers(path, binary_file_arch)

def class_symbols(path):
  symbols = {}
  #class symbol fORMat from nm: 0000000103113f68 (__DATA,__objc_data) external _OBJC_CLASS_$_EpisodeStatusDetailItemView
  re_class_name = re.compile('(\w{16}) .* _OBJC_CLASS_\$_(.+)')
  lines = os.popen('nm -nm %s' % path).readlines()
  for line in lines:
    result = re_class_name.findall(line)
    if result:
      (address, symbol) = result[0]
      symbols[address] = symbol
  return symbols

def filter_super_class(unref_symbols):
  re_subclass_name = re.compile("\w{16} 0x\w{9} _OBJC_CLASS_\$_(.+)")
  re_superclass_name = re.compile("\s*superclass 0x\w{9} _OBJC_CLASS_\$_(.+)")
  #subclass example: 0000000102bd8070 0x103113f68 _OBJC_CLASS_$_TTEpisodeStatusDetailItemView
  #superclass example: superclass 0x10313bb80 _OBJC_CLASS_$_TTBaseControl
  lines = os.popen("/usr/bin/otool -oV %s" % path).readlines()
  subclass_name = ""
  superclass_name = ""
  for line in lines:
    subclass_match_result = re_subclass_name.findall(line)
    if subclass_match_result:
      subclass_name = subclass_match_result[0]
    superclass_match_result = re_superclass_name.findall(line)
    if superclass_match_result:
      superclass_name = superclass_match_result[0]

    if len(subclass_name) > 0 and len(superclass_name) > 0:
      if superclass_name in unref_symbols and subclass_name not in unref_symbols:
        unref_symbols.remove(superclass_name)
      superclass_name = ""
      subclass_name = ""
  return unref_symbols

 for unref_pointer in unref_pointers:
    if unref_pointer in symbols:
      unref_symbol = symbols[unref_pointer]
      if len(reserved_prefix) > 0 and not unref_symbol.startswith(reserved_prefix):
        continue
      if len(filter_prefix) > 0 and unref_symbol.startswith(filter_prefix):
        continue
      unref_symbols.add(unref_symbol)

script_path = sys.path[0].strip()
f = open(script_path+"/result.txt","w")
f.write( "unref class number:  %d\n" % len(unref_symbles))
f.write("\n")
for unref_symble in unref_symbles:
  f.write(unref_symble+"\n")
f.close()