[__NSCFNumber length]: unrecognized selector sent to instance 0xb000000000000022

2015-07-28 16:34:24.374 EzPlug[1532:602143] -[__NSCFNumber length]: unrecognized selector sent to instance 0xb0000000000000222015-07-28 16:34:37.367 EzPlug[1532:602143] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFNumber length]: unrecognized selector sent to instance 0xb000000000000022'*** First throw call stack:(0x1823a82d8 0x1940240e4 0x1823af3a4 0x1823ac154 0x1822aeccc 0x186e29d98 0x1001618fc 0x100160c44 0x10015d20c 0x10015a178 0x100166188 0x1001052bc 0x100104698 0x10019e7c4 0x100135570 0x100500fd4 0x100500f94 0x100505c28 0x18235f7f8 0x18235d8a0 0x1822892d4 0x18bce76fc 0x186e86f40 0x1001f0bc8 0x1946cea08)libc++abi.dylib: terminating with uncaught exception of type NSException发生这种错误的原因是：在调用一个拥有length方法的NSString对象时，你传给他的是一个NSNumber对像。你可以通过设置一个break on exceptions，然后找到length方法在哪里被调用。如何设备异常断点，我的前两篇文章有详细介绍，这里就不多收了。