While there isn't any hard limit to the size of breadcrumb that can be set, larger breadcrumbs will increase the transmission size of the crash data.
Additionally, only the most recent 16 entries will be recorded.
*When using iOS SDK 1.27 or later, the maximum is 128, and for each breadcrumb, the message is limited to 140 characters, with a maximum size of 1KB. The breadcrumb is recorded without meta-data when the breadcrumb size exceeds 1KB.
public static void leaveBreadcrumbs(java.lang.String breadcrumb)