ios5 - kCTSuperscriptAttribute does not work in iOS -

i using kctsuperscriptattribute attributed string super script. works fine in view controller when call same method draw rect of custom view not work.

nsmutableattributedstring* astring =  [[nsmutableattributedstring alloc] initwithstring:@"will work in ios 5"];  nsmutableattributedstring *temp = [[nsmutableattributedstring alloc] initwithstring:@"2"]; cgfloat 2 = 1; cfnumberref twocfnum = cfnumbercreate(null, kcfnumbercgfloattype, &two);  [temp addattribute:(nsstring *)kctsuperscriptattributename value:(__bridge id)(twocfnum) range:nsmakerange(0, temp.length)]; [astring appendattributedstring:temp]; 

this ones tricky one. b appreciated.