ios - Locking with Obj-C -

i'm getting confused how locking works in obj-c.

i have network request want call once @ same time. want block other calls until has received data.

my lock of type nscondition , static, _sending bool. implementation. getwithsuccess using afnetworking perform action network requests, think can start multiple threads or using magic in gdc.

my problem implementation give me deadlocks, , need hint how correct implementation should work.

[lock lock];  while (_sending)     [lock wait];  _sending = yes;  [self getwithsuccess:^(nsurlrequest *request, nshttpurlresponse *response, id json) {     _sending = no;      [lock signal];     [lock unlock];   } fail:^() {     _sending = no;      [lock signal];     [lock unlock]; }]; 

i've accomplished similar using nsoperation , nsoperationqueue. depending on needs, can subclass nsoperation , check if operation of type in queue before adding new 1 (to prevent duplicate calls) or put network requests in queue , execute in order, 1 @ time setting maxconcurrentoperationcount 1

you mentioned using afnetworking has nsoperation subclass called afurlconnectionoperation might suit needs well.