Crash app for Contact

http://prntscr.com/jghnn6

my app getting a crash when I click People icon on my iPhone 5c

```2018-05-11 12:32:54.099220+0300 VM-Chat[417:98235] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'NSConcreteMutableAttributedString initWithString:attributes:: nil value'
*** First throw call stack:
(0x1d9efb3d 0x1cc77067 0x1d9efa85 0x1e252491 0x21e347 0x21e81b 0x220309 0x215017 0x2294d9 0x2291d9 0x228279 0x8c447d 0x21b657 0x1f94403 0x1f85453 0x1f89d47 0x1d9abd69 0x1d9a9e19 0x1d8fd1af 0x1d8fcfd1 0x1f0a7b41 0x22c85a53 0x1833e3 0x1d0ea4eb)
libc++abi.dylib: terminating with uncaught exception of type NSException
warning: could not execute support code to read Objective-C class data in the process. This may reduce the quality of type information available.```

how i can fixed it i really bad in obj-c

thanks