方法一:
if([[dictionary allKeys] containsObject:key){
// contains key}
方法二:
if([dictionary objectForKey:key]){ //objectForKey will return nil if a key doesn't exists.
// contains key}
方法一:
if([[dictionary allKeys] containsObject:key){
// contains key}
方法二:
if([dictionary objectForKey:key]){ //objectForKey will return nil if a key doesn't exists.
// contains key}