Posting your code would help, but looking at the raw data from that endpoint I'd caution you that JSON objects are enclosed in {}, and this is enclosed in [], indicating an array of JSON objects of length 1 in this case, rather than a single object.
Data is attached for easy reference
[
{
"id": "bitcoin",
"name": "Bitcoin",
"symbol": "BTC",
"rank": "1",
"price_usd": "7483.33",
"price_btc": "1.0",
"24h_volume_usd": "4643940000.0",
"market_cap_usd": "128416000716",
"available_supply": "17160275.0",
"total_supply": "17160275.0",
"max_supply": "21000000.0",
"percent_change_1h": "-0.0",
"percent_change_24h": "0.87",
"percent_change_7d": "19.56",
"last_updated": "1532102899",
"price_cad": "9845.0359947",
"24h_volume_cad": "6109547014.12",
"market_cap_cad": "168943525054"
}
]