iOS-AFNetworking源码解析（五）

AFURLRequestSerialization

AFURLRequestSerialization是用来对发出的请求进行一些处理

AFPercentEscapedStringFromString方法将string里面的:#[]@!$&’()*+,;=字符替换成%

NSString * AFPercentEscapedStringFromString(NSString *string) {
  	static NSString * const kAFCharactersGeneralDelimitersToEncode = @":#[]@"; // does not include "?" or "/" due to RFC 3986 - Section 3.4
    static NSString * const kAFCharactersSubDelimitersToEncode = @"!$&'()*+,;=";
	
  	// 从可用字符替换删除掉:#[]@!$&'()*+,;=这些字符
    NSMutableCharacterSet * allowedCharacterSet = [[NSCharacterSet URLQueryAllowedCharacterSet] mutableCopy];
    [allowedCharacterSet removeCharactersInString:[kAFCharactersGeneralDelimitersToEncode stringByAppendingString:kAFCharactersSubDelimitersToEncode]];

	// FIXME: https://github.com/AFNetworking/AFNetworking/pull/3028
    // return [string stringByAddingPercentEncodingWithAllowedCharacters:allowedCharacterSet];
	
  	// 声明批量处理的大小为50
    static NSUInteger const batchSize = 50;

    NSUInteger index = 0;
    NSMutableString *escaped = @"".mutableCopy;
	
  	// 循环将string里面:#[]@!$&'()*+,;=的字符替换成%
    while (index < string.length) {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wgnu"
        NSUInteger length = MIN(string.length - index, batchSize);
#pragma GCC diagnostic pop
        NSRange range = NSMakeRange(index, length);

        // To avoid breaking up character sequences such as